The San Diego field guide
Identifying the species is the first step toward a thoughtful solution. Get to know common ants, their habits, and the clues they leave behind.
Small creatures.
Big connections.
Featured species / 01
Linepithema humile
A common invader. A big reason we’re here.
Small, adaptable, and often seen in long trails, Argentine ants are a familiar sight around San Diego homes and irrigated landscapes.
Read the field notesLook closer.
Your neighborhood field guide
Open a field note to learn what to look for.
Long, continuous trailsLinepithema humile
Where to look: Homes, yards, and irrigated landscapes.
Often seen in long, busy trails. Connected colonies can make a property-wide approach especially important.
Need help identifying it? →
Larger workers; wood-associated nestsCamponotus spp.
Where to look: Wood, trees, and structures.
Some species excavate wood for nests. They do not eat wood; identifying nesting conditions is part of understanding the problem.
Need help identifying it? →
Distinctive odor when crushedTapinoma sessile
Where to look: Indoors, under debris, and near moisture.
A small ant sometimes recognized by a distinctive odor when crushed. Use several characteristics together for identification.
Need help identifying it? →
Nests around paving and soilTetramorium spp.
Where to look: Sidewalks, driveways, and soil.
Look for activity around cracks in paving and small soil deposits near entrances to a nest.
Need help identifying it? →
Stinging ants; identification mattersSolenopsis spp.
Where to look: Open ground and soil nests.
Some fire ants sting. Avoid disturbing a suspected nest and request identification before choosing a treatment.
Need help identifying it? →
Tree-associated trailsLiometopum occidentale
Where to look: Trees, wood, and nearby structures.
Often associated with trees and woody nesting sites. Follow activity back toward the surrounding landscape.
Need help identifying it? →Illustrations and symbols are for orientation. Several characteristics are needed to identify an ant; a close-up photo or inspection can help. Learn more in the UC IPM ant guide.
Details lead to better solutions
Look at overall size and whether the body is uniform or bicolored.
Are the ants moving in a steady trail or scattered around a space?
Notice nearby soil, wood, moisture, cracks, and vegetation.
Take a clear photo without disturbing a nest or handling the ants.
Our little corner of California
From coastal neighborhoods to inland communities, we’re here to help.
A closer look is a good place to start
Local knowledge. A thoughtful plan. A little peace of mind.