Start with the pest

Mice and rats get in through gaps the width of a pencil, nest in wall cavities and roof spaces, and gnaw wiring.

Most ant callouts are a trail to a food source. Carpenter ants are the exception: they excavate damp structural timber and are a building problem, not a kitchen one.

A nest in an eave, roof space or wall cavity is the most common emergency callout in this trade, and the one people least want to handle themselves.

Almost always a nuisance rather than a hazard, with two exceptions in North America: black widow and brown recluse.

The most expensive pest problem a building can have, and the least visible. Damage is structural and is generally not covered by home insurance.

Raccoons, squirrels, skunks and bats in roof spaces, chimneys and under decks. Legally distinct from insect work in most states and provinces, and often seasonally restricted while young are dependent.

A yard problem rather than a building one, and the clearest case of a recurring seasonal service rather than a single visit.

Honey bees are treated differently from wasps. Many operators will relocate a colony rather than destroy it, and some will not take the job at all.

Fleas usually arrive with a pet and survive in carpet and soft furnishing. Ticks are a yard and perimeter problem and carry real disease risk.

German cockroach is the difficult one — it breeds fast indoors and is the most common reason a treatment has to be repeated.

Travel-borne and stubborn. The pest most often treated by heat rather than chemistry, and the one where a cheap first treatment most often fails.

Pantry beetles and weevils in dry goods, clothes moths in wool and carpet, and the general run of silverfish, earwigs and millipedes that come in from damp.

Pigeons and starlings roosting on ledges, in signage and in roof spaces. The droppings are the health issue and the nesting material is the fire risk.

Nearly always a breeding source rather than an entry problem — a drain, a bin, a dead animal in a cavity, or an over-watered plant.