Pest control guides

Mail-order predators and nematodes are marketed as a chemical-free way to deal with greenhouse pests, but they are living animals that work only in narrow conditions. The Royal Horticultural Society (RHS) publishes a page on biological control in the garden that explains what to expect. This article summarises it, together with the RHS pages on aphids and on indoor-plant sap feeders where they add detail. It reflects RHS gardening advice for UK gardens and greenhouses, not a legal standard, and it is general information. It does not recommend particular suppliers or products.

What biological control is, according to the RHS

The RHS says the biological controls available to home gardeners are either predators or pathogenic nematodes, and that they can give effective management of some plant-damaging garden invertebrates. It lists advantages over pesticides, which are usually broad spectrum:

• they cause no damage to plants and leave no residues;
• once established, natural enemies can breed until the pest is reduced to an acceptable level;
• parasitoids are usually specific to certain prey and will not harm non-target creatures;
• they can be used where sprays would scorch plants or where no synthetic pesticides exist for some food plants;
• normal glasshouse jobs such as ventilating and watering are not affected, although pesticides must be avoided; and
• the target animals do not develop resistance.

It also lists cautions. Some predatory mites, bugs and beetles are generalists and should be used with care, and nematodes are usually insect-specific or mollusc-specific but can infect non-target animals within those groups, so they should be used in a targeted way.

Parasitoids and predators: why timing matters

The RHS explains that many of the “predators” sold are more accurately parasitoids, which lay eggs in a host and kill it only when their grub has finished developing. From that it draws two practical rules. Predators and parasitoids rarely give instant reductions in pest numbers because they need time to multiply, so they should be introduced before large pest populations develop. Conversely there is no point releasing them before the pest is active, since they can breed only when prey is present. Its aphid page follows the same logic: in spring, aphid populations rise before natural enemies are active in large numbers.

Temperature and season in the glasshouse

According to the RHS the effective season for predators and parasitoids in glasshouses is late March or April to September. They need warm conditions, generally daytime temperatures of at least 21 degrees C (70 degrees F) and high light intensity to stimulate breeding, although they can usually survive at 13 degrees C (55 degrees F). Glasshouse biological controls often die out over winter, so reintroduction may be needed every year. The indoor-plant page makes a related point about mealybug controls: they need relatively high temperatures, so are likely to be effective only from May to September. It adds that biological controls are most suitable for a glasshouse situation.

Pesticides and predators do not mix

The RHS says predators and parasites are very susceptible to most pesticides, which should be avoided. It gives persistence figures: pesticides can kill biological controls and persist for at least six weeks, for example ten weeks for deltamethrin-based products. It adds that natural organic pyrethrum can be used up to seven days before predator release, while pesticides based on fatty acids and plant oils or extracts can be used with care up to the day before biological controls are introduced. It also says fungicide use should be kept to a minimum. Its pages repeat that the RHS does not support pesticide use and recommends non-chemical options wherever needed.

How nematodes work and how to use them

The RHS describes the nematodes sold as controls as species that infect insects or molluscs. They enter the pest’s body and release bacteria, causing a fatal infection, and then feed and multiply on the decomposing body. The RHS says these species pose no risk to plants or vertebrates. Practical points it lists:

• Nematodes come in packs that are mixed with water and watered onto plants and soil.
• Being living organisms, they should be used as soon as possible after purchase and all manufacturers’ instructions followed.
• They generally need moist conditions and are best applied in cool, damp weather.
• Species differ in temperature needs, requiring temperatures above either 5 degrees C (41 degrees F) or 12 degrees C (54 degrees F).
• They should be used with care and only when there is a specific problem to treat.

Where they can be bought

Because they are living animals, most biological controls cannot be stocked on shop shelves and are usually supplied by mail order. The RHS says the exceptions are formulations of some nematodes used against ants, chafer grubs, leatherjackets, slugs and vine weevil larvae, which some retailers stock. Success depends on following the supplier’s release and aftercare instructions carefully, and the RHS offers a downloadable list of biological controls and their suppliers.

Matching the control to the pest

The RHS page lists controls pest by pest, and the site has separate articles on several of the pests involved: ants and aphids in the garden, glasshouse red spider mite and glasshouse whitefly and Encarsia wasps.

Questions people ask

Can predators be released straight after spraying? According to the RHS, pesticides can persist for at least six weeks, with shorter gaps only for pyrethrum and for fatty-acid, plant-oil or plant-extract products.

Will they stay all year? The RHS says glasshouse controls often die out in winter and may need reintroducing.

The bottom line

According to the RHS, biological control works when the release is timed early, the greenhouse is warm and bright enough, and pesticides have been kept away for the gap the RHS gives. Nematodes need moisture, the right temperature and prompt use, and both groups are living animals that usually come by mail order.

Sources

• Royal Horticultural Society, “Biological Control in the Garden” (rhs.org.uk)
• Royal Horticultural Society, “Indoor plants sap feeders: Identify” (rhs.org.uk)
• Royal Horticultural Society, “Aphids” (rhs.org.uk)

Brush against a tomato plant in a greenhouse and a cloud of tiny white insects lifts off the leaves. That is the usual introduction to glasshouse whitefly, a sap-feeding insect that breeds fast under glass and on houseplants. The Royal Horticultural Society (RHS) sets out how to recognise it, how it arrives and how it can be managed without pesticides. This article summarises the RHS page on glasshouse whitefly and its page on sap-feeding insects on indoor plants. It covers greenhouses and houseplants in the UK, reports RHS gardening advice rather than a legal standard, and is general information.

What glasshouse whitefly is

The RHS says whiteflies are sap-sucking true bugs in the family Aleyrodidae. Adults are typically white and fly up from host plants. About eight species are found in Britain, some limited to a narrow host range and others found indoors on many plants. Glasshouse whitefly (Trialeurodes vaporariorum) feeds on many greenhouse vegetables and ornamentals as well as houseplants, and the RHS names cucumber, melon, tomato, peppers, chrysanthemum, gerbera, pelargonium, fuchsia, lantana, poinsettia and verbena.

It thrives in warm conditions, which the RHS gives as the reason it is not usually a problem on outdoor plants, and it is active all year round on houseplants and in greenhouses. The RHS adds that outdoor plants can host it, especially in warm summers, but whiteflies on brassicas, Viburnum tinus, honeysuckle, evergreen azalea and rhododendron are other species specific to those plants.

How to recognise it

The RHS says whiteflies are relatively easy to see. When a plant is disturbed, clouds of small white-winged insects about 1.5 mm long fly up, which distinguishes whitefly from insects such as aphids. White objects on the top surface of leaves are more likely to be aphid skins. On the underside of leaves there may be flat, oval, creamy-white scale-like nymphs. If those nymphs are black, the RHS says they have probably been parasitised by an Encarsia wasp and are dead.

Adults and nymphs excrete sticky honeydew, which falls on foliage, stems and fruit and lets black sooty moulds grow. The RHS says it can be recognised as a black or brown powder on upper leaf surfaces and that sooty mould is usually a tell-tale sign of an insect infestation.

Why it builds up so quickly

The life cycle explains the speed. According to the RHS, adults and nymphs live on the undersides of leaves and feed on sap, weakening the plant. Females lay grey-white cylindrical eggs singly or in circles on leaf undersides, and each can lay more than 200 eggs. Males are rare and reproduction takes place without fertilisation. The eggs hatch into crawling nymphs that move around briefly before becoming fixed and feeding, and the final nymphal stage is the pupa, from which the adult emerges.

Temperature sets the pace: at 10 degrees C the life cycle takes several months, but it can be completed in about three weeks at 21 degrees C. In an unheated greenhouse the insect can stay active through winter if suitable host plants are present, whereas the RHS says it does not usually survive winter outdoors. Warm greenhouses can produce many generations in a season.

What the RHS advises

The RHS’s management steps are practical and non-chemical:

• Watch new purchases. The insect is often first brought into a glasshouse on new plants, so if possible new plants should be quarantined to give eggs and nymphs a chance to develop and be recognised.
• Remove unwanted plants from the glasshouse to cut the number of host plants.
• Provide good ventilation, which helps check the growth of sooty mould.
• Clean glasshouses in winter to reduce overwintering populations.

On indoor plants it refers readers to its indoor sap-feeder advice, which adds that manual removal is difficult for whitefly adults because of their mobility, and that the RHS does not support pesticide use.

Encarsia and other biological control

The RHS calls the introduction of tiny parasitoid wasps, Encarsia formosa, an established method of control. The wasps prey on the whitefly’s scale-like nymphs and can be bought by mail order from biological control suppliers. Two points matter for timing. First, the parasitoid must be introduced before plants are heavily affected, because it cannot give instant control. Second, parasitised nymphs turn black, so progress is easy to monitor. The RHS says other predators, such as the mite Amblyseius andersonii, which preys on eggs, are sometimes available in addition. The indoor page adds that all biological controls are susceptible to pesticides and so cannot be used with most pesticidal controls.

Yellow sticky traps

The RHS suggests hanging sticky yellow sheets above or among plants to trap adult whitefly, but it frames them as a way of monitoring whitefly activity rather than controlling it. It warns that sticky traps often catch non-target organisms, including the parasitoid wasps released as biological control, so their use should be considered carefully. On the indoor-plant page it says sticky traps are less likely to catch other insects inside the home, though they may not look attractive.

Whitefly versus other pests

The RHS page says white objects on the top of leaves are more likely to be aphid skins, and its aphid page notes that woolly aphids can be confused with scale insects, mealybug or whitefly. The site’s related RHS-based articles cover ants and aphids in the garden, glasshouse red spider mite and mealybugs and scale insects on houseplants.

The bottom line

According to the RHS, glasshouse whitefly is a warm-conditions pest that usually enters on new plants and multiplies fast in a heated greenhouse. Quarantining purchases, thinning surplus plants, ventilating and cleaning in winter are the first steps, and Encarsia formosa wasps are the established biological control if introduced early.

Sources

• Royal Horticultural Society, “Glasshouse Whitefly: Identification and Control” (rhs.org.uk)
• Royal Horticultural Society, “Indoor plants sap feeders: Identify” (rhs.org.uk)

Two of the most persistent houseplant pests look nothing like insects. Mealybugs hide under cottony white wax, and scale insects sit still under shell-like covers that resemble small bumps on a stem. The Royal Horticultural Society (RHS) publishes separate pages on each, plus a page on sap-feeding insects on indoor plants. This article summarises those three pages. It reports RHS gardening advice for houseplants, conservatories and greenhouses in the UK, not a legal standard, and it is general information.

What each pest is

The RHS describes glasshouse mealybugs as sap-sucking true bugs typically covered in a white waxy material, closely related to scale insects and often considered unarmoured scale insects. Most species prefer moist, warm climates, and those in the UK are typically found in glasshouses and other protected places. They live in clusters in inaccessible spots such as leaf axils, leaf sheaths, between twining stems and under loose bark. Some species, mostly Rhizoecus, feed on roots, and the RHS says these are also confined to glasshouses and houseplants, apart from the golden root mealybug, which can survive on roots outdoors.

Scale insects are described as many species that suck sap from garden and glasshouse plants in Britain, ranging from under 1 mm to over 1 cm across. More than 25 species occur in British gardens. All have a waxy shell-like covering when mature. Several are confined to houseplants and to greenhouses and other sheltered places, while others live on ornamentals and fruit trees outdoors.

Signs to look for

For mealybugs the RHS says the usual first sign is fluffy white wax in leaf axils or other sheltered places, with the insects or their orange-pink eggs underneath. Large numbers cause an accumulation of sticky honeydew, which encourages black sooty mould. Heavy infestations can reduce vigour, stunt growth and cause premature leaf fall. Plants named as commonly affected include cacti and succulents, African violets, bougainvillea, citrus, fuchsia, grape vines, hoya, orchids (especially Phalaenopsis), oleander, passion flower, peach and tomato.

For scale insects the signs are shell-like bumps on stems and the underside of leaves, poor growth where populations are large, honeydew on upper leaf surfaces and, in early summer, eggs under a covering of white waxy fibres. The RHS warns that the white egg masses of cushion scales can be mistaken for mealybug or woolly aphid. On the indoor-plant page it adds that indoor scale insects often sit close to the midrib or main veins on the underside of leaves.

How they arrive

The RHS’s clearest message is that these pests usually arrive on new plants. Female mealybugs do not fly or crawl far, and the RHS says the same about the adult females of scale insects. Its advice is to inspect new purchases carefully, and where possible to quarantine them, keeping new plants apart from the existing collection. For mealybugs the mealybug page suggests isolation of at least a month before adding acquisitions to an existing collection. Quarantine gives eggs and nymphs a chance to develop and be recognised, and populations time to grow enough to be spotted without risk to other plants.

What the RHS says to do

The RHS approach is tolerance first, then proportionate action:

• Tolerate where possible. Plants can tolerate some mealybug, although populations can build quickly if left unchecked, and well-tended healthy plants tolerate light populations of scale insects.
• Monitor houseplants often so action can be taken before damaging populations develop.
• Separate affected plants from unaffected ones to limit spread.
• Remove adult scales and egg masses when seen, although the RHS says this may not reduce a large population.
• Clear dead leaves and pruning waste from greenhouses and around houseplants, since these may carry mealybugs or eggs.
• Consider moving plants that tolerate UK outdoor conditions outside, where the insects become accessible to natural predators or cooler conditions can slow their life cycles.
• Dispose of heavily affected plants. The RHS says replacing plants heavily affected by scale or mealybugs can be simpler than trying to eliminate the insects, and says the same in its mealybug advice.

Manual removal has limits. The indoor-plant page notes that mealybugs are hard to remove by hand because of where they hide.

Biological controls

For mealybugs the RHS says a ladybird, Cryptolaemus montrouzieri, can be released into greenhouses and that its larvae look like large mealybugs. Both adults and larvae find and eat mealybugs and eggs in confined spaces. Parasitic wasps of the genera Leptomastix, Leptomastidea and Anagrus are sometimes available, and can give control where population levels are fairly low. The ladybird and wasps need relatively high temperatures, so are only likely to succeed from May to September.

For soft scale the RHS says the nematode Steinernema feltiae can be bought from some biological control suppliers. Nematodes can infect non-target animals, so they should be used with care and only when there is a specific problem to treat. Outdoors, it says some ladybirds, parasitoid wasps and birds eat scale insects. On the indoor page it adds that all biological controls are susceptible to pesticides and cannot be used alongside most pesticidal controls, and that the RHS does not support pesticide use.

Greenhouse or living room

The RHS says scale insects in greenhouses can breed continuously throughout the year, whereas species on outdoor plants mostly have one generation a year. Glasshouse mealybugs are active all year on houseplants and in greenhouses.

Questions people ask

Do biological controls suit a flat with a few plants? The RHS says they are most suitable for a glasshouse situation.

The bottom line

The RHS treats mealybugs and scale insects as pests that arrive on new plants and then persist in warm, protected places. Inspecting and quarantining purchases, tolerating light populations, isolating affected plants and being willing to bin a heavily infested one are its main recommendations, with biological controls for greenhouses in the warmer months.

Sources

• Royal Horticultural Society, “Mealybug (Glasshouse): Identification & Control” (rhs.org.uk)
• Royal Horticultural Society, “Scale Insects: Identification and Control” (rhs.org.uk)
• Royal Horticultural Society, “Indoor plants sap feeders: Identify” (rhs.org.uk)

Fine pale speckling on the upper side of tomato, cucumber or pelargonium leaves, followed by dry, dropping foliage, is a classic sign of a mite that many gardeners meet each summer. The Royal Horticultural Society (RHS) describes glasshouse red spider mite as one of the most troublesome problems of greenhouse plants and houseplants. This article summarises the RHS’s page on the mite. It relates to greenhouses, gardens and houseplants in the UK, it reports the RHS’s gardening advice and not any legal requirement, and it is general information.

What the mite is

The RHS identifies glasshouse red spider mite (also called two-spotted spider mite, Tetranychus urticae) as a sap-sucking mite. Mites belong to the arachnids, and most are under 1 mm long. This one pierces plant tissue and feeds on cell contents, causing a mottled appearance and, in severe cases, leaf loss and plant death.

Its host range is wide. The RHS names vines, peaches, nectarines, cucumbers, tomatoes, aubergines, peppers, fuchsias, pelargoniums, poinsettias, orchids and impatiens, and says the range is so wide that few plants are completely immune. It thrives in warm, dry conditions and is usually a problem from March to October, though damage can occur at other times in a heated greenhouse. It can also cause problems outdoors in summer, especially in hot, dry weather.

Recognising it

The RHS lists these signs:

• a fine pale mottling on the upper leaf surface;
• many tiny yellowish-green mites, white cast skins and egg shells on the underside of leaves, easier to see with a x10 hand lens;
• in heavy attacks, fine silk webbing on the plant, with leaves that lose most of their green colour and dry up or fall.

Despite the name, the mites are usually yellowish-green with two dark patches. They may be entirely dark, and they typically turn orange-red only in autumn and winter, or when a plant has become uninhabitable because of their feeding. The RHS says adults are up to 1 mm long, just visible to the naked eye in large numbers, and are usually on the lower leaf surface with their spherical eggs.

Why it takes off in warm, dry greenhouses

The RHS explains that mature orange-red females spend the winter resting in cracks and crevices such as glasshouse frames, stakes, canes, soil and plant debris. From late March they start feeding and laying eggs. Breeding can be continuous from March to October. The life cycle length depends on temperature: about 55 days at 10 degrees C, but complete in about 12 days at 21 degrees C. Severe damage can therefore develop quickly in warm, dry conditions, and the RHS says plants grown at high temperatures in dry, overcrowded glasshouses are more liable to serious problems.

Prevention and clearing out

For management, the RHS says regular syringing or spraying of plants with water and keeping humidity high reduce the risk, but will not control the mite on their own. Its other steps are to:

• remove severely affected plants from glasshouses, especially in late summer before cooler temperatures and shorter days send females to shelter for winter;
• clear plant debris, old canes, stakes and plant ties before spring to reduce overwintering mites;
• clean empty glasshouses thoroughly with a glasshouse disinfectant; and
• keep weeds in and around the glasshouse in check, since they may act as hosts.

The RHS refers gardeners with the mite on indoor plants to its separate page on sap-feeding insects on indoor plants. Its indoor-plant page says the RHS does not support pesticide use, recommends non-chemical options wherever needed, and notes that biological controls are susceptible to pesticides and so cannot be used with most of them.

Biological controls the RHS lists

The RHS says several biological controls are available by mail order:

• Phytoseiulus persimilis, a predatory mite. This is the most commonly used control. It is about the same size as the pest (0.5 mm) but has an orange-red pear-shaped body, is more active and taps the leaf surface with its front legs while hunting. It feeds on all life stages of the mite and is dispatched as nymphs and adults to be released in sheltered positions on infested plants. The RHS notes it does not control fruit tree red spider mite on apple and plum, but can succeed against glasshouse red spider mite on outdoor plants in summer.
• Amblyseius californicus, a predatory mite. The RHS says it is a less efficient predator and less likely to control heavy infestations, but can be used as a preventative control out of season. It can also feed and breed on other prey and even pollen, and is more likely than Phytoseiulus to survive winter in a glasshouse.
• Feltiella acarisuga, a predatory midge native to Britain. Adults are small black flies and the larvae eat the mites. The RHS says it can be used in spring before heavy infestations develop, only if it is suspected the mite has overwintered, and is less likely to work in hot, dry summer conditions.
• Atheta (Dalotia) coriaria, a 3 to 4 mm dark brown rove beetle. It feeds on a wide range of invertebrates, including fungus gnats and thrips, and is sometimes sold for red spider mite management.

The RHS also provides a downloadable list of biological control suppliers on its page.

The bottom line

According to the RHS, glasshouse red spider mite is a warm-and-dry problem: keep humidity up, clear out debris and weeds, remove badly affected plants late in the season and, if a predator is used, match the species to the timing and the conditions. It regards damping down as helpful but not a control by itself, and it does not support pesticides.

Sources

• Royal Horticultural Society, “Glasshouse Red Spider Mite: Prevention Tips” (rhs.org.uk)
• Royal Horticultural Society, “Indoor plants sap feeders: Identify” (rhs.org.uk)

Clusters of greenfly on a rose shoot with ants running up and down the stem is one of the most familiar sights in a UK garden, and it often prompts a search for pest control. The Royal Horticultural Society (RHS) publishes separate advice pages on aphids and on ants, and they explain why the two are connected and why the RHS generally recommends tolerance. This article summarises those two pages. It covers gardens in the UK, describes RHS advice rather than legal requirements, and is general information. Ants inside a building are a different problem, covered in the site’s article on ants indoors and why identification matters before treatment.

What aphids are

The RHS describes aphids as sap-sucking true bugs, 1 to 7 mm long. Some are the familiar greenfly or blackfly, but there are yellow, pink, white and mottled species. It says there are more than 500 aphid species in Britain, that some feed on only one or two plant species while others use many, and that almost any plant can host them, including ornamentals, vegetables, fruit, greenhouse plants and houseplants. Most feed on foliage, stems and flowers, but some feed on roots. A few species, such as those on poplar, cause galls, and woolly species can be confused with scale insects, mealybug or whitefly.

What the damage looks like

Colonies can usually be seen with the naked eye, often on shoot tips, flower buds and the underside of younger leaves. Symptoms the RHS lists include stunted growth, curled or distorted leaves, sticky honeydew on which black sooty mould grows, and white cast skins on the upper leaf surface. The RHS says sooty mould can be wiped off with a damp cloth and that aphids very rarely kill plants. It does flag that some aphids transmit plant viruses, which is a particular problem on soft fruit such as strawberry and raspberry, on some vegetables including tomatoes and members of the cucumber and marrow family, and on ornamentals such as dahlias, lilies, pelargoniums, tulips and sweet peas. Virus-affected plants should be destroyed to prevent spread.

Where ants come in

The RHS ant page says ants collect the honeydew that aphids and some other sap-feeding insects excrete. Ants can protect aphids from ladybirds and other predators to secure the supply, and the aphid page adds that ants tend the aphids and remove aphid predators. On the ant page the RHS notes that increased aphid numbers may mean more damage to plants. The aphid page adds that ants found climbing a plant may be tending an aphid colony.

Ants have their own effects. According to the RHS they do little direct damage, but they can disturb soil around roots and push excavated soil to the surface during nest building. That can be an issue on lawns and where low-growing plants are buried by soil. Ants may also disturb roots in pots and containers, and this disturbance can make plants more prone to wilting when dry at the roots. Nests are frequent in lawns, flower pots, compost bins and among plant roots. The RHS says an ant nest in a compost heap or bin is not causing damage in that situation. It adds that some ants, mostly Myrmica or “red ants”, can sting, though for most people this is no more than a minor irritation. More than 30 species are found in Britain, and the black garden ant Lasius niger is the familiar one in gardens.

The RHS position on control

On aphids, the RHS says to tolerate them where possible, that it is usual to have some in a healthy garden, and that they are a vital food source for wildlife. It says gardeners do not have to kill or control them. If control is wanted, its answer to whether to use pesticides is no, because most pesticides, including organic types, reduce biodiversity including natural enemies, affect soil health and have wider environmental effects. The steps it lists are:

• check plants frequently so that action can be taken before damage develops;
• squash colonies with finger and thumb;
• encourage natural enemies such as ladybirds, ground beetles, hoverflies, parasitoid wasps and earwigs, noting that spring aphid populations rise before enough natural enemies are active, so waiting often lets them do the work; and
• not bother trying to control aphids on trees, where natural enemies normally reduce numbers.

The RHS adds that some natural enemies, including hoverfly larvae, lacewing larvae and several parasitoid wasps, can be bought as biological control for greenhouses.

For ants, the RHS says they should be tolerated wherever possible and that unless nests are particularly troublesome they are best left alone. It also warns that if a colony is destroyed, incoming queen ants are likely to take over the territory and may establish even more new nests.

Lawns, pots and nematodes

For lawn ant heaps the RHS advises brushing the excavated soil away on a dry day before mowing, because otherwise the mower smears the soil on the surface. If years of ant activity have made the lawn uneven, it suggests peeling back turf on the raised areas, removing excess soil and relaying the turf, which is easier in winter when ants are less active. Where control is judged necessary, it says a pathogenic nematode, Steinernema feltiae, is available from some suppliers of biological controls for treating nests in lawns and flower beds. The nematodes are watered into the soil where ants are bringing soil to the surface, and the RHS says they may also affect non-target insects.

The bottom line

The RHS treats aphids and ants as connected parts of a garden’s wildlife rather than problems to be eliminated: ants farm aphids for honeydew, aphids seldom kill plants and pesticides do more harm than good in its view. Squashing colonies, brushing away lawn ant heaps and letting natural enemies build up are its first-line options for UK gardens.

Sources

• Royal Horticultural Society, “Aphids” (rhs.org.uk)
• Royal Horticultural Society, “Ants in the Garden: Helpful or Harmful?” (rhs.org.uk)

Bottles of “natural” ant, mosquito or flea spray on US shelves often have no EPA registration number, while conventional pesticides do. That is not an oversight. The US Environmental Protection Agency (EPA) exempts a category it calls “minimum risk pesticides” from registration under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). This article summarises three EPA pages on the exemption: “Minimum Risk Pesticide: Definition and Product Confirmation” (last updated 8 April 2026), “Conditions for Minimum Risk Pesticides” and “State Regulation of Minimum Risk Pesticides” (last updated 23 September 2026), plus EPA’s enforcement page. It covers the United States only, and it is general information. EPA’s own pages note that they give guidance to manufacturers and distributors and do not create binding requirements.

What the exemption is

EPA says certain minimum risk pesticides pose little to no risk to human health or the environment, so it has exempted them from the requirement to register under FIFRA. The exemption is in 40 CFR 152.25(f). EPA says it began exempting such products in 1996 to reduce cost and regulatory burden for businesses and the public for pesticides posing little or no risk, and to focus its resources on pesticides that pose greater risk. The exemption covers products meant to control pests such as mosquitoes, ticks, rats and mice as well as products used in agriculture.

The six conditions

EPA lists six conditions that a product must meet to qualify:

• Active ingredients: only those listed in 40 CFR 152.25(f)(1).
• Inert ingredients: only those EPA has classified as eligible, meaning ingredients listed in 40 CFR 152.25(f)(2), commonly consumed food commodities, animal feed items, edible fats and oils, and certain chemical substances listed under 40 CFR 180.950(e).
• Label listing: all active and inert ingredients must appear on the label, with active ingredients by label display name and percentage by weight.
• No health-related claims: the product must not bear claims to control or mitigate organisms that pose a threat to human health, or insects or rodents carrying specific diseases.
• Company details: the producer’s name and contact information must be displayed prominently.
• No false or misleading statements on the label.

A product that meets all six conditions does not need to be registered with EPA. If it fails any of them, EPA says it is not exempt and its sale or distribution without registration may violate FIFRA unless another exemption applies.

What labels may and may not say

The health-claim condition shapes what a shopper will see. EPA says minimum risk labels may not link a pest to a specific disease. It gives examples: a label may not say it “controls ticks that carry Lyme disease”, but may say it “controls ticks”; it may not say it controls mosquitoes that can transmit malaria, encephalitis, West Nile virus or Zika virus, but may say it “controls mosquitoes”. Labels also may not claim to control microorganisms that threaten human health, so terms such as “sterilize”, “disinfect”, “sanitize” or “kill germs” are outside the exemption, as are claims to “prevent infection” or “stop the spread of germs and disease”. For a shopper, a bottle that makes any of these claims and carries no EPA registration number is a mismatch with the exemption as EPA describes it.

What EPA does not do

EPA says it generally does not review products that claim to meet the exemption, and it does not provide label review. The producer is responsible for reading the criteria and judging whether the product meets them. That means the absence of a registration number, and the presence of a “minimum risk” description, reflect the producer’s own evaluation of the criteria rather than an EPA approval of that specific product.

States can still require registration

EPA states that a product exempt federally may still require registration under state law. It explains that each state has its own statutes and regulations on pesticide registration, sales and use, and that states are not required to permit the sale of a product simply because it is exempt under FIFRA. Questions on state rules are best directed to the state pesticide regulator. So a product on sale in one state may face different requirements in another.

Enforcement

EPA says that if a product does not meet all the requirements and is sold anyway, it must be registered unless another exemption applies, and that EPA may issue notices of warning, stop sale, use or removal orders, and assess civil or criminal penalties. States also monitor the market, may take their own enforcement action and may refer misleading product claims to the Federal Trade Commission.

Common questions

Does “minimum risk” mean a product is harmless?

EPA says it has determined that such products pose little to no risk to human health or the environment when they meet the exemption criteria. The label and manufacturer’s directions still apply.

Where do registered products fit?

Registered products carry an EPA registration number and follow a different path, described in the site’s guide to reading a US pesticide label.

The bottom line

EPA exempts minimum risk pesticides from federal registration if they meet six conditions on ingredients, labelling and claims, and it does not review individual products. States can still require registration. For a US household, an unregistered spray with no health claims and a full ingredient list fits the exemption on its face, while one promising to kill disease-carrying insects or germs does not. Anyone comparing DIY products with a quote from a professional should check the label first.

Sources

• US EPA, “Minimum Risk Pesticide: Definition and Product Confirmation” (epa.gov)
• US EPA, “Conditions for Minimum Risk Pesticides” (epa.gov)
• US EPA, “State Regulation of Minimum Risk Pesticides” (epa.gov)
• US EPA, “Enforcement Related to Minimum Risk Pesticides” (epa.gov)

Wasp nests under eaves, pigeons on a roof edge, squirrels in a chimney or gulls on a flat roof all mean a pest controller working above ground level. For a business, landlord or facilities manager who books that work, the Health and Safety Executive (HSE) says the rules on working at height matter: falls from ladders and through fragile roofs are among the biggest causes of workplace death and serious injury. This article summarises HSE’s guidance on work at height, mainly its leaflet INDG401 “Working at height: A brief guide” (a web version of a January 2014 revision) and its web pages on ladders and common myths. HSE is Great Britain’s workplace health and safety regulator, so this covers Great Britain. It is general information and not a substitute for HSE’s own guidance or professional advice.

What counts as work at height

HSE’s FAQ says work at height means work in any place where, if precautions were not taken, a person could fall a distance liable to cause personal injury. It gives examples: working above ground or floor level, working where a person could fall from an edge, through an opening or fragile surface, or into an opening in a floor or a hole in the ground. Walking up and down a permanent staircase in a building is not work at height. Working on a ladder or a flat roof counts, as does anywhere a person could fall through a fragile surface.

Who the Work at Height Regulations 2005 apply to

HSE says the Regulations apply to employers and to those who control any work at height activity, giving contractors and factory owners as examples. Its FAQ adds that duties can fall on facilities managers or building owners who contract others to work at height. Employers and those in control must ensure work is properly planned, supervised and carried out by competent people, using the right equipment. HSE says the Regulations require that all work at height is properly planned and organised, that those involved are competent, that risks are assessed, that the risks of working near fragile surfaces are managed, and that equipment is inspected and maintained. Low-risk, relatively straightforward tasks need less planning effort.

The three-step hierarchy

HSE’s brief guide sets out a sequence to follow before anyone works at height:

• Avoid work at height where it is reasonably practicable to do so, by doing as much work as possible from the ground. Its examples include extendable tools used from ground level so no one has to climb a ladder.
• Prevent falls where work at height cannot be avoided, using an existing safe place of work or the right type of equipment.
• Minimise the distance and consequences of a fall where the risk cannot be eliminated.

The guide says collective protection, such as a guard rail, that works without the person doing anything should be considered before personal protection such as a harness, which depends on the individual using it correctly.

Ladders

HSE says ladders are not banned. It describes them as a sensible option for low-risk, short-duration tasks, and its FAQ gives 30 minutes at a time as a guide: if a task needs more than that on a leaning ladder or stepladder, consider alternative equipment. On the “myths” page it says a ladder user needs to be competent, not formally qualified. It says ladders should be used only where they can be level and stable and, where reasonably practicable, secured. When both hands are needed briefly on a stepladder, HSE says to keep three points of contact at the working position, which can be two feet and the body supported by the stepladder. A ladder used to reach another level should extend at least one metre above the landing point so there is a secure handhold, be of a suitable industrial grade and be tied.

Roofs and fragile surfaces

The leaflet says roof work is high risk and that falls from roofs, and through fragile roofs and roof lights, are among the most common causes of workplace death and serious injury. It says these accidents occur on roofs of factories, warehouses and farm buildings as well as in construction, when repair or cleaning is under way. HSE lists as likely to be fragile: roof lights, liner panels on built-up sheeted roofs, non-reinforced fibre cement sheets, corroded metal sheets, glass including wired glass, rotted chipboard, and slates and tiles. It says the place where work will be done must be checked every time before use, that weather conditions that could compromise safety must be taken into account, and that emergency and rescue plans should not rely entirely on the emergency services.

What this means when booking a pest job

• Ask whether the contractor has assessed the access route and method, and whether ground-level options such as extendable tools or non-roof solutions can do the job.
• For commercial buildings, warehouses or farms, tell the contractor about fragile roof lights or sheeting before the visit.
• Expect a contractor to use suitable equipment and to be competent, since HSE says the Regulations require it. The site’s piece on asbestos and roof void access covers a separate check that may apply before roof-space work.

These are practical questions drawn from HSE’s duties on planning and competence; they are not a legal test of any particular contract. For choosing a contractor more generally, see the site’s guide to choosing a pest controller.

Common questions

Does HSE ban ladders for roof or gutter work?

No. HSE says ladders and stepladders are not banned and can be used for low-risk, short-duration tasks or where existing features cannot be altered.

Must a ladder user hold a formal qualification?

HSE says no: the requirement is competence, meaning the skills, knowledge and experience to use the ladder properly, or working under competent supervision.

The bottom line

HSE’s position is that height work should be avoided if reasonably practicable, that fall prevention comes before fall protection, and that ladders remain acceptable for low-risk, short jobs when used competently. Fragile roofs are the standout hazard. For anyone booking a pest job that involves roofs or lofts in Great Britain, the practical takeaway is to expect planning, competence and suitable equipment from the contractor.

Sources

• HSE, “Working at height: A brief guide” (INDG401) (hse.gov.uk)
• HSE, “Work at height: Frequently asked questions” (hse.gov.uk)
• HSE, “Common work at height myths” (hse.gov.uk)
• HSE, “Safe use of ladders and stepladders” (hse.gov.uk)

Pest control contracts are often agreed in the home, at the moment a technician has found a problem, and the customer may want to change their mind afterwards. In the UK, the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 govern cancellation rights for contracts made at a distance or off the trader’s premises, and legislation.gov.uk shows their extent as the whole United Kingdom. This article walks through the provisions that matter most for a pest control booking: the 14-day cancellation period, the exception for urgent repairs, what happens if work has started, and what a consumer must do to cancel. It is general information, not legal advice, and it does not replace the wording of the Regulations or a consumer adviser.

Which contracts the cancellation right covers

Regulation 29 says a consumer may cancel a distance or off-premises contract at any time in the cancellation period without giving a reason and without liability, except in limited cases such as where the consumer asked for early supply of the service. Regulation 5 defines an off-premises contract to include a contract concluded with the trader and consumer physically present in a place that is not the trader’s business premises, such as the consumer’s home, and a contract for which the consumer made the offer in the physical presence of the trader away from business premises. A distance contract is one made under an organised distance sales or service scheme, without the trader and consumer physically together, using only means of distance communication up to the moment of contracting, for example a booking made entirely by phone or online.

The 14-day period

For a service contract, regulation 30 says the cancellation period ends at the end of 14 days after the day on which the contract is entered into. If the trader has not given the consumer the required information on the right to cancel, regulation 31 extends the period. If the trader supplies that information within 12 months, the period ends 14 days after the consumer receives it. Otherwise, it ends at the end of 12 months after the day it would have ended under regulation 30.

The urgent-repairs exception

Regulation 28 lists circumstances where the cancellation rules do not apply. Paragraph (1)(e) covers contracts where the consumer has specifically requested a visit from the trader for the purpose of carrying out urgent repairs or maintenance. So if a household calls a company because of an urgent problem and asks it to attend, that contract is not subject to the cancellation period. The site’s article on describing an urgent pest situation covers how to record what was asked for.

Regulation 28(2) narrows the exception. It says the exception does not stop the cancellation rules applying to a contract for services in addition to the urgent repairs or maintenance requested, or for goods other than replacement parts necessarily used in the repairs, if the trader supplies them on the occasion of such a visit. In a pest control context, an extra service sold during the visit, such as an annual contract added on top of an urgent callout, is therefore treated differently from the urgent treatment requested.

If work starts inside the cancellation period

Regulation 36 covers services supplied during the period. A trader must not begin the service before the end of the cancellation period unless the consumer has made an express request, and for an off-premises contract, has made it on a durable medium such as paper or email. If the consumer then cancels after a service has begun in response to that request, regulation 36(4) says they must pay an amount for the service supplied up to the time the trader is told of the cancellation, in proportion to what has been supplied compared with the full contract. It is calculated on the total price agreed, or on the market value of the service supplied if the total price is excessive.

The consumer bears no cost, under regulation 36(6), if the trader failed to give the required information about the right to cancel or about payment of that cost, or if the service was not supplied in response to a proper request. Regulation 36(2) also says the right to cancel is lost if the service has been fully performed, provided performance began after such a request and with an acknowledgement that the right would be lost once the contract was fully performed. A one-off treatment completed in a single visit could therefore end the right to cancel, but only if these conditions were met.

How to cancel

Regulation 32 says the consumer must inform the trader of the decision to cancel. They may use the model cancellation form in the Regulations or make any other clear statement of the decision. It says a consumer who sends a communication is treated as having cancelled in the period if it is sent before the period ends, and that in a dispute it is for the consumer to show the contract was cancelled in time. Keeping a dated copy of an email or letter is therefore sensible.

Common questions

Does the 14 days apply to every pest control booking?

The cancellation right applies to distance and off-premises contracts. A contract made entirely on the trader’s own premises falls outside these provisions, and the urgent-repairs exception in regulation 28(1)(e) can apply to a visit the consumer specifically requested.

Where do quality complaints fit?

Cancellation is separate from complaints about the standard of work. The site’s guide to the Consumer Rights Act 2015 and pest control contracts covers that route.

The bottom line

Under the 2013 Regulations, which extend across the UK, a consumer has 14 days after agreeing a distance or off-premises pest control service to cancel without giving a reason, but there is an exception where the consumer specifically requested an urgent visit. If work has begun in the cancellation period on a proper request, the consumer pays a proportionate amount. Cancelling clearly and in writing, and keeping a copy, is the safest course. Compare quotes first through the site’s guide to choosing a pest controller.

Sources

• legislation.gov.uk, Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013, regulation 5 (definitions)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 28 (circumstances excluding cancellation)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 30 (normal cancellation period)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 31 (cancellation period extended for breach of information requirement)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 29 (right to cancel)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 36 (supply of service in cancellation period)
• legislation.gov.uk, Consumer Contracts Regulations 2013, regulation 32 (exercise of the right to cancel)

Mosquitoes breed in water, and the yard of a US home often holds more of it than the owner expects. The US Environmental Protection Agency (EPA) publishes guidance on how households and communities should control mosquitoes, built around integrated pest management (IPM). This article summarises three EPA pages: “Success in Mosquito Control: An Integrated Approach” (last updated 8 October 2025), “Controlling Mosquitoes at the Larval Stage” (last updated 26 February 2026) and “Bti for Mosquito Control” (last updated 2 June 2026). It covers the United States only, since registered products and rules differ elsewhere, and it is general information. The UK equivalent, which is about reporting and standing water, is covered in the site’s piece on mosquito control and standing water.

The four-part approach EPA describes

EPA says effective mosquito management means intervening at some point in the mosquito life cycle, and that the best approach uses every life stage through IPM, which it describes as a science-based approach focused on prevention, reduction and eliminating the conditions that lead to infestations. It also says IPM relies heavily on resident education and monitoring, and that a successful strategy can include pesticides. It names four tactics: remove mosquito habitats, use structural barriers, control mosquitoes at the larval stage and control adult mosquitoes.

Tactic one: remove habitats around the home

Because mosquitoes need water for two stages of their life cycle, EPA says an important part of control around homes is giving them nowhere to lay eggs. Its list is practical:

• Get rid of standing water in rain gutters, old tires, buckets, plastic covers, toys and any other container.
• Empty and change the water in bird baths, fountains, wading pools, rain barrels and potted-plant trays at least once a week.
• Drain temporary pools or fill them with dirt, and keep swimming pool water treated and circulating.

EPA notes that Aedes aegypti mosquitoes lay eggs in containers with wide openings holding water with organic material such as decaying leaves, prefer dark containers in the shade, and can use sites as small as bottle caps. It adds that egg and larva interventions are generally the most effective and least costly way to control mosquitoes, but that they are unlikely to be 100 per cent effective, especially for species that breed in varied and scattered locations, so habitat removal needs supplementing.

Tactic two: structural barriers

Because Aedes mosquitoes frequently bite indoors, EPA says barriers reduce bites. It lists installing window and door screens where they are missing, making sure screens are “bug tight”, and covering gaps in walls, doors and windows. Its Puerto Rico example also mentions netting over baby carriers and beds.

Tactic three: larvicides

EPA says larvicides target larvae in breeding habitat before they mature and disperse, which it describes as maximising the effect of pesticide use while minimising widespread application. It says choosing which larvicide to use in a given area is best done by experts, depending on factors such as risk, cost, resistance and ease of use. The main groups it describes are bacterial insecticides (Bacillus species), insect growth inhibitors such as methoprene, oils and films that form a thin layer on the water surface, and the organophosphate temephos. It says temephos is labelled only for use by public health officials or mosquito abatement personnel, and that EPA issued a cancellation order for all its uses in February 2011, with the manufacturer barred from selling temephos products after 31 December 2015.

Bti: the larvicide sold to homeowners

EPA describes Bti (Bacillus thuringiensis subspecies israelensis) as a naturally occurring soil bacterium whose toxins specifically affect the larvae of mosquitoes, blackflies and fungus gnats. It says EPA has registered five strains in 48 pesticide products for residential, commercial and agricultural use, primarily against mosquito larvae. EPA says Bti can be used around homes in containers and places where water collects, such as flower pots, tires and bird baths, and on larger waters such as ponds and irrigation ditches. It says a number of Bti products are sold as “homeowner” products, that no special precautions are needed for applying them, and that people do not need to leave treated areas. Its published conclusion is that Bti does not pose a risk to humans and has minimal toxicity to honey bees, and that there is no documented resistance to Bti as a larvicide. EPA also stresses following the label for any Bti product: some are allowed for certain drinking water such as cisterns while others are not. These are EPA’s conclusions about the product class; the label of the specific product governs use.

Tactic four: adult mosquitoes

EPA says chemical control of adult mosquitoes is legitimate in certain circumstances, especially when disease is being transmitted or when habitat removal and larval control have failed or are not feasible. Adulticides are applied by aircraft or truck-mounted sprayers as ultra-low-volume sprays. EPA says choosing an adulticide is a job best done by experts, and that decisions on where and when to spray are made by local officials, who announce dates and locations in their communities. This is a public programme, not a household treatment.

Common questions

Does EPA say larvicides are safe for a garden pond?

EPA says Bti can be used on larger bodies of water such as ponds and irrigation ditches and that products differ, so the label decides which uses are allowed.

Is screening enough?

EPA lists screens as one of four tactics and says a successful strategy combines several.

The bottom line

EPA’s guidance treats mosquito control as a sequence: remove standing water, screen the home, treat breeding water with a registered larvicide where needed and leave adult spraying to local programmes. Bti products sold for homes are the larvicide EPA describes most fully, and EPA says the label of any product controls where it can be used. Homeowners weighing DIY against a contractor should ask what the contractor will do at each stage.

Sources

• US EPA, “Success in Mosquito Control: An Integrated Approach” (epa.gov)
• US EPA, “Controlling Mosquitoes at the Larval Stage” (epa.gov)
• US EPA, “Bti for Mosquito Control” (epa.gov)

In the United States, the rat and mouse poison on a hardware-store shelf is different from what a pest control company may use in the same house, and the difference is set by the Environmental Protection Agency (EPA) under federal pesticide law. This article summarises three EPA pages on rodenticides: “Restrictions on Rodenticide Products” (last updated 8 September 2026), “Safely Use Rodent Bait Products” (last updated 6 October 2025) and “Rodent Control Pesticide Safety Review”. It applies to the United States only; UK and Irish rules differ, as covered in the site’s articles on professional and consumer rodenticide access in the UK and Ireland’s professional registration. This is general information. A licensed pest professional or the product label should always be the reference for a particular treatment.

Three groups of active ingredients

EPA’s safety review sorts eleven rodenticide active ingredients into three groups. First-generation anticoagulants are warfarin, chlorophacinone and diphacinone. Second-generation anticoagulants are brodifacoum, bromadiolone, difenacoum and difethialone. Non-anticoagulants are bromethalin, cholecalciferol, strychnine and zinc phosphide. EPA says second-generation anticoagulants are especially hazardous for wildlife and pets because they are highly toxic and persist in body tissues, and because a rodent can feed several times before dying, so carcasses can carry residues that a predator or scavenger might eat.

What EPA says consumers can buy

According to EPA, rodent poisons sold to consumers are ready-to-use bait stations, with bait in block or paste form secured inside the station, and loose or pelleted bait is no longer permitted in consumer products. Where a station is refillable, up to one pound of bait may be packaged with it, and non-refillable stations must be disposed of properly once the bait has been eaten or contaminated. EPA says consumer products may not contain the four second-generation anticoagulants, which are registered only for the commercial and structural pest control markets. Pest control professionals may still use baits with those ingredients in homes.

The two EPA pages differ slightly on which active ingredients consumer bait stations may contain. The “Restrictions” page lists bromethalin, chlorophacinone and diphacinone as those currently registered, while the “Safely Use” page lists bromethalin, chlorophacinone, cholecalciferol, diphacinone, warfarin and zinc phosphide as permitted. Because the pages carry different update dates and list different ingredients, the product label is the authority on what a given box contains.

EPA says consumer stations are labelled for use either indoors, or indoors and outdoors within 50 feet of buildings, depending on whether the station has been shown to resist tampering by young children and dogs and to resist weather. It says to read the label to be sure the product suits the place where it will be used.

What professionals and farms can use

EPA says professional and agricultural products are registered for use in or near buildings, within 100 feet of structures, and in or near agricultural buildings. They may not be sold in consumer outlets such as drug, grocery or hardware stores. Second-generation anticoagulant products must be sold in containers of at least 16 pounds if labelled for professional applicators and at least eight pounds if labelled for use in or near agricultural structures. Professional and agricultural products with first-generation anticoagulants, bromethalin, cholecalciferol or zinc phosphide must be sold in containers of at least four pounds. Their labels require tamper-resistant bait stations wherever children under six, pets or non-target wildlife can reach the bait, and for all outdoor above-ground applications. Baiting of outdoor burrows is permitted only with pelleted bait placed at least six inches down active rat burrows.

The 2008 decision and proposed changes

EPA’s review page says a 2008 risk mitigation decision set the one-pound package limit for the consumer market, barred second-generation anticoagulants from consumer products and required tamper- and weather-resistant stations for outdoor above-ground placements where children, pets and wildlife may be present. In November 2022, EPA issued proposed interim decisions for eleven rodenticides under registration review. These are proposals, not final rules. They include classing all second-generation anticoagulant, strychnine and zinc phosphide products as restricted use pesticides, restricting the sale and use of larger packs of several other products to trained and certified users, prohibiting refillable bait stations in consumer-sized products, and requiring carcass search and disposal after some uses. EPA said the documents would go out for a 75-day public comment period, and the next step was an interim decision.

Safe-use points EPA gives to households

• Read and follow the label directions and store pesticides away from children and pets, for example in a locked utility cabinet or shed.
• Place baits and traps only where children and pets cannot reach them, and never store pesticides next to food, including pet food.
• Promptly remove and dispose of dead rodents, to prevent accidental poisoning of wildlife and pets that might eat a carcass.

Common questions

Can a US homeowner buy the same poison a pest company uses?

Not for the second-generation anticoagulants. EPA says they are registered for commercial and structural pest control only, and that professional-market products are not to be sold in consumer stores.

Are the 2022 proposals in force?

EPA describes them as proposed interim decisions that were open for public comment. They are proposals unless and until EPA finalises them.

The bottom line

EPA limits US consumers to bait stations with block or paste bait in packs of one pound or less and excludes the four second-generation anticoagulants from those products, reserving them for professionals. Labels decide where a product may be used, and EPA’s 2022 proposals for tighter controls were still proposals on its review page. Anyone weighing a DIY product against a professional visit should read the label first and treat the regulatory tiers as a reason to compare the options.

Sources

• US EPA, “Restrictions on Rodenticide Products” (epa.gov)
• US EPA, “Safely Use Rodent Bait Products” (epa.gov)
• US EPA, “Rodent Control Pesticide Safety Review” (epa.gov)