I’ve treated for many ant species across the U.S., and the one thing I’m 100 percent sure of is this: It’s hard to generalize about baiting, even within the same species. At one residential account, I encountered satellite colonies of odorous house ants (Tapinoma sessile)that differed in their food preferences. I’ve also seen Argentine ants (Linepithema humile) that wouldn’t take any gel or liquid bait presented to them at 7 a.m., then gradually began foraging on the bait after several hours. In other words, even a tried-and-true bait will “fail” from time to time.
One reason may be that ants aren’t interested in foraging at the time. In the Argentine ant example above, it may be that the trails we encountered were focused on brood movement, establishing new satellite colonies, or something else. Other times, it may be that ants have access to a resource they prefer over a particular bait. I’ve seen ants foraging on conifer scales that wouldn’t touch any gel baits, but ants foraging on citrus scales devoured it.
A final note: Heat breaks down active ingredients. Try to keep your bait under 100 degrees Fahrenheit to help prevent breakdown.