Which pest do I have? The comparisons that settle it
Before treating, you have to know what you are treating: method, price and urgency change completely from one species to the next. Here are the six most frequent mix-ups on the South Shore, with the details that settle them in a minute.
Mouse or rat?
| What to check | House mouse | Norway rat |
|---|---|---|
| Body length | 65 to 95 mm | 200 to 250 mm, tail shorter than the body |
| Droppings | 3 to 6 mm, rice-grain shaped | 15 to 20 mm, capsule shaped |
| Opening needed | 6 mm | 20 mm and up |
| Where you find them | walls, cabinets, basement | burrows outside, under decks, near garbage |
A young rat looks like a mouse, but its head and feet are too big for its body.
Detailed pages: Mice: the full page · Rats: the full page
Carpenter ant or black ant?
| What to check | Carpenter ant | Small black ant |
|---|---|---|
| Size | 6 to 13 mm, often several sizes in one colony | 2 to 3 mm, all alike |
| Thorax in profile | smoothly rounded, one curve | uneven, bumpy |
| Clues | fine sawdust, sounds in wood, winged ants in spring | trails to food, no sawdust |
| Risk | tunnels through damp structural wood | nuisance, no structural damage |
Winged ants indoors in late winter almost always mean a nest inside the building.
Detailed pages: Carpenter ants: the full page
Bed bug, flea or carpet beetle?
| What to check | Bed bug | Flea | Carpet beetle larva |
|---|---|---|---|
| Look | 4 to 7 mm, oval, reddish brown, cannot jump | 1 to 3 mm, flattened side to side, jumps far | hairy larva, 4 to 5 mm, moves slowly |
| Where you see it | mattress seams, headboard, baseboards | on the pet, carpets, lower legs | carpets, closets, under furniture |
| Bites | at night, often in a line on the upper body | ankles and lower legs | does not bite; contact can irritate skin |
| Pet involved | not necessary | almost always | unrelated |
With no insect found, bites alone confirm nothing: the inspection settles it.
Detailed pages: Bed bugs: the full page · Fleas: the full page
Wasp, honey bee or bumblebee?
| What to check | Yellowjacket | Honey bee | Bumblebee |
|---|---|---|---|
| Look | smooth, bright yellow and black, narrow waist | golden brown, hairy | large, very hairy, yellow and black bands |
| Nest | grey paper, ground or eaves | hive, wall or tree cavity | ground, rock garden, old bird nest |
| Behaviour | drawn to food and garbage | around flowers | slow, peaceful away from the nest |
| What to do | treat if the nest is near a walkway | call a beekeeper | leave it if possible, the nest dies in the fall |
A hover fly looks like a small wasp, but it hovers in place and does not sting.
Detailed pages: Wasps and hornets: the full page · Bees and bumblebees: the full page
Cockroach or another brown insect?
| What to check | German cockroach | Earwig | Silverfish |
|---|---|---|---|
| Look | 12 to 16 mm, two dark stripes behind the head | 12 to 20 mm, pincers at the rear | 10 to 15 mm, silvery, three tail filaments |
| Where | kitchen and bathroom, near heat | under pots, mulch, door sills | bathroom, damp basement, cardboard boxes |
| Activity | avoids light, mostly at night | at night, comes in under doors | at night, very fast |
| Urgency | high in an apartment: treat the building | low | low, a moisture question |
A single cockroach seen in daylight often means an established population.
Detailed pages: Cockroaches: the full page · Earwigs: the full page · Silverfish: the full page
House centipede, sowbug or millipede?
| What to check | House centipede | Sowbug | Millipede |
|---|---|---|---|
| Look | 15 pairs of long legs, very fast | grey, domed plated back | cylindrical, brown, curls up |
| Diet | other insects | plant debris | plant debris |
| Indoors | can settle in if it is damp | dies quickly in dry air | dies quickly in dry air |
| What it reveals | plenty of prey and moisture | basement moisture | mulch and leaves against the foundation |
All three point to the same cause: a basement or foundation perimeter that is too damp.
Detailed pages: Sowbugs and centipedes: the full page
Still unsure? Take a photo of the insect or the damage and describe what you see in the form at the bottom of this page: the request is routed by your town. An identification from a photo avoids paying for the wrong treatment.