What can I spray for ants and other critters?
Nobody—not even an entomologist like me—wants to see critters in their home, office, school, or favorite restaurant. But see them we do. And unfortunately, the first reaction most people have is to reach for a can of bug spray and hose the place down.
But what does this really accomplish? Two things: a quick kill of only the critters you sprayed, and you’ve now left a coating of pesticides wherever you sprayed. Satisfied? Probably not, since your goal is to solve the problem, not just kill a few critters. If so, then put down the bug spray and walk away—slowly.
When we think of pests, we might imagine them as vile creatures that are intentionally tormenting us. The truth, however, is that pests are always there for a reason. Maybe they are inside because they found a gap leading to a safe place to spend the winter (think brown marmorated stink bug, ladybug, or boxelder bug). Or maybe your gutters are clogged and there is a moisture problem inviting to carpenter ants. Or you have overripe bananas with the stem torn at the top, exposing the fruit within, and now you see fruit flies. While it’s true that a spray might kill pests—so too can a swift shoe.
But if we want to develop a solution that addresses the issue and prevents future problems, we must follow two simple steps:
Inspection. Where are the pests found and how did they get there? It might feel like your whole house is infested, but with a thorough inspection you can often find the source of a problem by looking for where the critters or their evidence are most numerous. If you can find the source of where they are feeding or breeding, chances are you can do them in.
Identification. Knowing the identity of a pest tells you why it is there. It’s also a necessity for crafting a sound management plan. For example, this spring I received many calls about ants. Even when callers had tried sprays, they were ineffective. Why? Each pest is there for a different reason—and needs its own management approach.
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Carpenter ants trailing on the outside of a building might be moving from outdoor parent nests to indoor satellite nests. Case 1: Ants in Rental Home! Using a few pictures to determine size and the number of nodes, the ants were identified as carpenter ants, which do not actually eat wood. Instead, they excavate rotten wood to make their nests. This means carpenter ants indicate a moisture problem somewhere in the structure; an important problem you might not otherwise have known about. So in an oddball way, you owe them a debt of gratitude. And although parent nests are typically outdoors, satellite nests can be found inside buildings—so an inspection is needed to discover where the ants are living. This can be accomplished by baiting and tracking ants to the source, then eliminating the rotten wood and ant nest. For more details, see our carpenter ant fact sheet.
- Case 2: Ants in Bathroom! These ants are identified by how they smell when crushed. Their name? The odorous house ant (abbreviated OHA). They build nests in moist locations and forage indoors for spilled foods.
Odorous house ants can move their entire colony or split into several colonies — making it tough to deal with them. (Credit: Janet Hurley) Based on their biology, OHA can be difficult to manage because the colony is mobile—moving nest locations at will—and can actually split into multiple colonies if sprayed or for other reasons. To date, the best method to control OHA are certain baits that, when placed correctly, can be spread throughout the colony to achieve control.
- Case 3: Winged Ants Indoors! Known as citronella ants by their smell, this species isn’t really a pest of homes because they don’t eat what we eat, nor are they at home indoors. Instead they live in the soil and feed on secretions from root-feeding insects. But they can be a nuisance when winged ants emerge into homes. Since their sole purpose in life is finding a new place to live, spraying or baiting are pointless. To avoid problems down the line, you’ll need to eliminate the cracks and crevices where ants are getting inside.
Foraging pavement ants bring bait back to the nest and spread throughout the colony. They’re a great target for baits.
After you’ve found where the pests really are and ID’d them correctly, you can a develop short-term plan to reduce their numbers and long-term solutions that fix the conditions that allowed or enticed them in in the first place.
Need help identifying a pest? Here are some options:
- Collect a sample and visit our Pest Identification Key
- Cornell Cooperative Extension in each county (cost varies per sample)
- Insect Diagnostic Laboratory at Cornell University ($25 per sample)
- IdentifyUS (web-based identification)
To identify common structure infesting ants: