Ant Identification + Control
Why this matters
Ant calls are the #1 service request in residential pest control in spring + summer. Wrong species ID = wrong treatment = customer thinks the service failed. Carpenter ants damage structure; pavement ants are nuisance; fire ants sting; pharaoh ants split colonies + multiply under spray pressure. This is the species-by-species treatment reference.
ID the species first
A spray + walk approach kills the ants visible on the counter + leaves the colony untouched. ID drives the bait + the placement strategy.
Argentine ant (Linepithema humile)
- 1/8 inch, light to medium brown, no node petiole visible
- Trails along baseboards, plumbing, electrical
- Massive colonies; multiple queens; satellite colonies common
- Strong invasive pressure in CA, southern US
- Treatment: sweet bait (sugar-based - Optigard, Maxforce Quantum); broad gradient bait stations + non-repellent transfer chemistry (fipronil); spot foundation perimeter
Odorous house ant (Tapinoma sessile)
- 1/8 inch, dark brown to black; smells like rotten coconut when crushed
- Nest in walls, under foundations; multi-queen colonies split easily under spray
- DO NOT use repellent insecticides (drives splitting + creates worse problem)
- Treatment: sweet bait (Optigard, Advion); fipronil or thiamethoxam non-repellent applied perimeter
Pavement ant (Tetramorium caespitum)
- 1/8 inch, dark brown, two-node petiole, parallel grooves on head
- Nest in soil under pavement, sidewalks, foundation slab
- Trail into structures around plumbing penetrations
- Treatment: foundation perimeter granular bait OR liquid; spot indoor sweet + protein bait combo
Carpenter ant (Camponotus spp.)
- 1/4 - 5/8 inch (largest common house ant), black OR red + black
- Excavate wood for nesting (do NOT eat wood; create galleries); damage often resembles termite but with smooth, clean galleries + frass piles (sawdust + insect parts)
- Active dawn + dusk
- Treatment: locate the parent colony in or near structure (often in exterior tree, fence, woodpile); treat colony directly with non-repellent + locate any satellite colonies; spot foundation perimeter
Pharaoh ant (Monomorium pharaonis)
- 1/16 inch, yellow to light brown
- Indoor only; hospital + kitchen common
- BUDDING under spray pressure - sprays drive colony splits + multiply infestation
- Treatment: BAIT ONLY (Maxforce, Advion); NEVER spray; identify all colony locations + bait simultaneously; sanitation critical
Acrobat ant (Crematogaster spp.)
- 1/8 inch, dark, heart-shaped abdomen raised over head when disturbed
- Nest in wood (former carpenter ant galleries) + insulation + tree cavities
- Trail along utility lines into structures
- Treatment: locate + treat the nest directly; perimeter spray; sweet bait
Fire ant (Solenopsis invicta - imported red fire ant)
- 1/8 - 1/4 inch, reddish-brown, painful sting + mound nests in lawn
- Quarantine: imported fire ant federal quarantine in several southern states; fire-ant-positive nursery stock cannot ship out without certification
- Treatment: mound treatment (drench or granular) for spot work; broadcast bait (Amdro, Extinguish Plus) for whole-property + then mound follow-up
- Customer expectation: program approach over multi-year contract - total eradication unrealistic in fire-ant territory
Crazy ant (Nylanderia spp. - including tawny crazy ant)
- 1/8 inch, light brown, erratic + fast movement
- Spreading invasive across Gulf states; multiple queens; superficially trail along outdoor surfaces
- Difficult: most baits fail; perimeter sprays with non-repellent + adjacent landscape barrier
Ghost ant (Tapinoma melanocephalum)
- 1/16 inch, dark head + pale legs + abdomen
- Tropical species; common in FL, southern + warm-house indoor
- Treatment: sweet + protein bait rotation; multi-queen colony
Treatment decision matrix
| Species | Bait type | Spray approach | Special note |
|---|---|---|---|
| Argentine | Sugar | Non-repellent perimeter | Massive colonies, gradient approach |
| Odorous house | Sugar | NO repellent | Colony splits under repellent |
| Pavement | Sugar + protein | Perimeter granular OK | Slab penetration sealing |
| Carpenter | Protein | Direct colony treatment | Find parent colony |
| Pharaoh | Sugar + protein bait ROTATION | NEVER spray | Bait-only protocol |
| Acrobat | Sugar | Direct nest treatment | Often former carpenter galleries |
| Fire ant | Granular bait broadcast | Mound treatment | Program approach, multi-year |
| Crazy ant | Non-repellent + barrier | Less responsive to bait | Difficult; spread management |
| Ghost ant | Sugar + protein rotate | Light perimeter | Indoor multi-queen |
Procedure (standard ant treatment visit)
- Customer briefing - confirm what they're seeing, where, when (time of day; species often correlates)
- Trail-follow - locate active trail; follow to entry point + ideally to nest location
- Species ID - confirm via key characteristics
- Sanitation - note attractants (food residue, pet food, sugars, plumbing leaks)
- Treatment - per species
- Customer education - what to expect (initial spike in visible ants as colony recruits to bait, then collapse 7 - 21 days)
Spraying ANY repellent insecticide on an odorous house ant or pharaoh ant colony will multiply the problem. The colonies sense the chemical + split into multiple satellite colonies. You started with one problem; you now have five. ALWAYS ID the species before reaching for the spray rig. Repellent products (most pyrethroids - bifenthrin, lambda-cyhalothrin, permethrin) are the wrong tool here; use non-repellents (fipronil, thiamethoxam) or stick with bait.
Follow-up
- Light infestation: re-check 14 - 21 days
- Heavy or carpenter ant: re-check 7 - 14 days; locate + treat parent + satellite colonies
- Annual contracts: quarterly preventive perimeter + visit-on-call
References
- NPMA Field Guide to Structural Pests
- University extension ant ID guides (varies by region; UC IPM, Texas A&M AgriLife)
- EPA-registered ant control product labels
- Federal imported-fire-ant quarantine + state DOA enforcement
- Manuall internal: Integrated Pest Management Reference, German Cockroach IPM