5.8 Stinging Insects, Spiders, Ticks & Mites
Key Takeaways
- Section 71 (1) (c) of O. Reg. 63/09 lets a Structural class holder perform a land extermination of animals that bite, sting, are venomous or carry disease, and s. 16 names wasps and ticks in the public health or safety definition.
- Yellowjackets and hornets build enclosed paper nests and become aggressive scavengers in late summer, while paper wasps build a single open comb with no envelope.
- Social wasp nests are treated at dusk or dawn when foragers are home, and the entrance is left open until the colony is dead so returning wasps do not chew inward.
- The northern black widow occurs locally in Ontario, but the brown recluse is not established here, so almost every reported recluse bite in the province has another cause.
- Bird and rodent mites bite people only after the host is removed, so mite complaints following a nest removal are a predictable consequence rather than a new infestation.
5.8 Stinging Insects, Spiders, Ticks & Mites
[!NOTE] This is the part of the structural licence that reaches outdoors. Section 71 (1) (c) of O. Reg. 63/09 exempts a Structural class holder so they may perform a land extermination of "pests that are animals that bite, sting, are venomous or carry disease", and s. 16 lists wasps, mosquitoes and ticks in the definition of promotion of public health or safety. The nest under the soffit and the tick in the client's yard are both within reach — provided the product and the placement are lawful.
Social Wasps and Hornets
All Ontario social wasps follow the same annual cycle: a mated queen overwinters alone, founds a nest in spring, raises workers through summer, produces reproductives in late summer, and the colony dies at frost. Nests are not reused the following year, which matters because clients pay to remove nests that are already dead.
| Species | Nest | Behaviour |
|---|---|---|
| Yellowjackets (Vespula spp.) | Enclosed paper envelope around multiple combs; in ground burrows, wall voids, soffits and hollow masonry | Aggressive; switch to scavenging sugars in late summer, which is when stings peak at patios and waste bins |
| Bald-faced hornet (Dolichovespula maculata) | Large grey football-shaped aerial nest with an envelope, in trees and under high gables | Very defensive near the nest |
| European paper wasp (Polistes dominula) | A single open comb on a stalk, no envelope; under eaves, in pipe ends, light fittings and barbecue burners | Less aggressive away from the nest, but often in high-contact locations |
| European hornet (Vespa crabro) | Enclosed nest in hollow trees and wall voids | Large, active at night, attracted to lights |
Solitary species are far less hazardous and often need no treatment: mud daubers (single mud tubes, docile), cicada killers (large solitary ground burrows) and carpenter bees (Xylocopa virginica), which bore a near-perfect round hole about 1.3 cm across into unpainted or weathered softwood and then tunnel along the grain. The hovering, territorial male carpenter bee has no sting at all.
Honey bees are a referral, not a target. Where a honey bee swarm or colony is found, contact a beekeeper for removal. Note also that if a colony in a wall void is killed, the abandoned comb and honey must be removed or it will ferment, stain, and attract a secondary infestation.
Treating a wasp nest safely
- Treat at dusk, night or dawn. Foragers are home, temperatures are lower and defensive flight is slower. A mid-afternoon treatment leaves a large share of the workforce untreated and airborne.
- Wear real protection — a bee suit or full coveralls with a veil, gloves and sealed cuffs. Ask about sting allergy in yourself and anyone present, and know where the client's epinephrine auto-injector is if they have one.
- Plan the retreat before you start, especially on a ladder. Never work directly beneath an aerial nest you are about to disturb.
- Match the tool to the nest. A jet aerosol for aerial nests; an insecticidal dust blown into the entrance for ground nests and wall voids, which is the most effective option because returning foragers carry it deep into the nest.
- Leave the entrance open until the colony is dead. Sealing a void entrance traps live wasps, which then chew inward and emerge inside the building. Seal only after activity has ceased, and then remove the nest material where accessible.
- Use a low-pressure, coarse application and avoid contaminating anything below the nest.
Spiders of Ontario Buildings
Almost all Ontario building spiders are harmless and beneficial. The common ones are cellar spiders (long fragile legs, irregular webs in basements), funnel weavers (sheet web with a retreat tube), orb weavers (classic wheel webs on exterior lighting), wolf spiders (hunters that do not build capture webs) and yellow sac spiders (pale, building small silken retreats at wall-ceiling junctions).
Two medically significant species dominate exam questions and client anxiety:
- Northern black widow (Latrodectus variolus) — glossy black, with a red hourglass or a row of red marks on the underside of the abdomen. It occurs in a limited number of Ontario localities, in undisturbed sheltered places such as rock piles, meter pits and outbuildings. Bites are rare; the venom is neurotoxic.
- Brown recluse (Loxosceles reclusa) — not established in Ontario. It has a violin-shaped mark on the cephalothorax and, diagnostically, six eyes in three pairs rather than eight. Specimens occasionally arrive in freight from its native range, but a self-sustaining population does not exist here.
[!IMPORTANT] Almost every "brown recluse bite" reported in Ontario is something else — a bacterial skin infection, another arthropod bite, or a non-bite lesion. Do not confirm a spider bite from a wound. Encourage medical assessment, and identify from a captured specimen or not at all.
Control is largely mechanical: remove webs and egg sacs, reduce clutter and exterior harbourage, seal entry, and change or reposition exterior lighting so it stops attracting the flying insects the spiders are eating. Residual application to harbourage is a supporting tactic, and glue boards in corners are effective monitors.
Ticks
- Blacklegged tick (Ixodes scapularis) — the vector of Lyme disease in Ontario, with an expanding established range. Nymphs are very small and are responsible for most transmission.
- American dog tick (Dermacentor variabilis) — larger, ornately marked; not a Lyme vector.
Ticks are acquired from vegetation, not from indoor harbourage, so there is no such thing as a purely indoor tick programme. Effective work is habitat modification: keep grass short, remove leaf litter and brush, create a dry mulch or gravel transition between woodland and lawn, move play equipment and seating away from woodland edges, and exclude the rodent and deer hosts where possible. A labelled perimeter acaricide is available where the label supports it.
Removal advice for clients: grasp the tick as close to the skin as possible with fine-tipped tweezers and pull steadily upward without twisting. Do not burn it, smother it in petroleum jelly, or crush the body. Wash the site and advise medical consultation, keeping the tick for identification.
Mites
| Mite | Source | Why people are bitten | Control |
|---|---|---|---|
| Bird mites (including Dermanyssus gallinae) | Pigeon, starling, sparrow or swallow nests | The host has been excluded or the nest removed, so mites disperse inward seeking blood | Remove nests and treat the void as one operation; see section 4.4 |
| Rodent mites (Ornithonyssus bacoti) | Rat and mouse nests | The rodent host has died or been removed | Complete the rodent programme, remove nest material, treat harbourage |
| Clover mites | Dense lawn and vegetation against a sunny wall | Mass spring invasion; not a biter but stains red when crushed | Bare strip of gravel or soil at the foundation; exclusion; vacuum indoors |
| Straw itch mites | Stored grain and dried plant material infested with insect larvae | Incidental bites when the material is handled | Remove or treat the infested commodity |
| House dust mites (Dermatophagoides spp.) | Mattresses, upholstery, carpets | They do not bite — they are an allergen source | Humidity control, allergen-proof encasements, hot laundering, HEPA vacuuming; not an insecticide target |
[!WARNING] A biting complaint with no bed bugs found is a diagnostic problem, not a treatment problem. Work through the list before applying anything: bird or rodent mites following a recent nest or carcass removal, bat bugs after a bat exclusion, fleas after a pet has gone, and non-arthropod causes such as low humidity, fibreglass fragments, paper dust or a medical condition. Applying pesticide to an occupied bedroom on the strength of an unexplained itch is both ineffective and indefensible.
Under Ontario Regulation 63/09 Section 71(1), a licensed structural exterminator is dispatched to treat an active paper wasp (Polistes spp.) nest under a residential porch roof. What operational timing should the technician observe to maximize safety and colony eradication?
A yellowjacket colony is nesting inside a hollow masonry wall with a single active entrance at a weep hole. What is the correct treatment approach?
A client in Ontario reports a necrotic skin lesion and is convinced it is a brown recluse bite sustained at home. What is the technician's correct response?