Common Residential Pest Identification
Overview
Quick-reference for identifying the pests techs encounter on residential service calls. Mis-identification leads to wrong chemistry, wrong protocol, wrong customer expectations. This card covers the 95 % of residential pest calls - the species you'll see daily.
Reference Table - Insects
Ants:
| Species | Visual | Size | Behavior signature |
|---|---|---|---|
| Odorous house ant | Dark brown, single node | 3 mm | Crushed = coconut/rotten smell |
| Argentine ant | Light brown, slow | 3 mm | Established trails along baseboards |
| Pavement ant | Dark, single node | 3 mm | Nests in pavement cracks |
| Carpenter ant | Black or red, large | 6 - 12 mm | Sawdust pile nearby = moisture damage |
| Pharaoh ant | Yellow/amber, very small | 2 mm | Multi-colony; near plumbing |
| Acrobat ant | Heart-shaped abdomen | 3 - 4 mm | Raises abdomen when disturbed |
| Fire ant | Reddish-brown | 3 - 6 mm | Aggressive, painful sting |
Cockroaches:
| Species | Color | Size | Habitat |
|---|---|---|---|
| German cockroach | Light brown | 13 - 16 mm | Indoor kitchens + bathrooms |
| American cockroach | Reddish-brown | 35 - 40 mm | Basements, sewers, large |
| Oriental cockroach | Dark, almost black | 25 mm | Moist basements + crawlspaces |
| Brown-banded cockroach | Banded pattern | 12 mm | Bedrooms + closets (drier than other roaches) |
| Smoky brown cockroach | Glossy dark brown | 30 - 35 mm | Outdoor primarily, occasional invader |
Spiders:
Most house spiders are harmless. Medically important species:
| Species | Identification | Note |
|---|---|---|
| Brown recluse | Violin shape on cephalothorax | Hides in dark; bites have necrotic potential |
| Black widow | Glossy black, red hourglass on underside | Bites cause systemic reactions |
| Hobo spider | Brown, fast-moving | Uncommon outside Pacific Northwest |
Other common pests:
- Silverfish: silver-gray, fast-moving, fish-shaped - indoor dampness
- Earwigs: pincers on rear - outdoor primarily, occasional invader
- Centipedes: many legs, fast - indoor moisture
- Stink bugs: shield-shaped, brown - fall invader
- Lady bugs (Asian lady beetle): orange/red, dots - fall invader
- Boxelder bugs: black with red markings - outdoor, fall invader
Reference Table - Rodents
| Species | Size | Color | Habitat | Notes |
|---|---|---|---|---|
| House mouse | 3 - 4" + tail | Grayish-brown | Indoor + outdoor | Most common residential mouse |
| Deer mouse | 3 - 4" + tail | Brown + white belly | Outdoor primarily | Hantavirus carrier |
| Norway rat (brown rat) | 7 - 10" + tail | Brown | Basements + lower levels | Most common urban rat |
| Roof rat (black rat) | 6 - 8" + tail | Black/brown, slim | Attics + upper levels | Southern + coastal regions |
| Eastern gray squirrel | 8 - 10" + tail | Gray | Attics + soffits | Considered "wildlife" - different regulatory path |
Reference Table - Wood-Destroying
| Species | Damage signature | Treatment |
|---|---|---|
| Subterranean termite | Mud tubes on foundations | Liquid barrier OR bait stations |
| Drywood termite | Pellet frass near small holes | Spot treatment OR fumigation |
| Formosan termite | Very aggressive subterranean | Specialty treatment |
| Carpenter ant | Wood shavings (not pellets) | Bait + colony elimination |
| Powderpost beetle | Tiny exit holes + flour-like dust | Specialty treatment |
Notes
- Identification matters MORE than chemistry choice. Wrong-species treatment is the #1 cause of "you came multiple times + it didn't work" complaints. Take photos + macro shots when you can't immediately ID.
- When in doubt, sample. A specimen in a vial can be identified by your shop's specialist or sent to extension service for ID.
- Customer-named pests are often wrong. Customers say "I have ants" when they have termites; "I saw a spider" when it was a daddy long-legs harvestman (not actually a spider). Verify visually before treatment.
- Some "pests" are beneficial. Spiders eat other pests; daddy long-legs are harmless; lady beetles eat aphids. Customer education on what NOT to treat is valuable.
The pest-identification app market has gotten good. iNaturalist + Picture Insect identify > 90 % of common residential pests from a photo. Use these when ID isn't immediately obvious - quicker than getting back to the shop's reference materials. Verify your AI identification before applying treatment; the apps are right most of the time, not all of the time.
References
- Mallis Handbook of Pest Control (industry standard reference)
- NPMA Field Guide to Structural Pests
- State extension service identification guides
- Manuall internal: Quarterly Residential Pest Service, Ant Trail Identification & Treatment, Identify Pest Entry Points