Dear Ant Experts,
I have a large colony of ants in my yard (or possibly many colonies) in Surprise, AZ. These ants are becoming a small problem because they love to bite my family. So far I have tried many "ant baits" and found that they ignore all of them except for amdro pellets which contain Hydramethylnon. Boiling water works great on them when I can locate their hills, but they always return. Any information on what kind of ants these are and how to eradicate them will be very appreciated! Thank you in advance!
I wish I had some encouraging news for you, but it's likely you have Solenopsis xyloni, a close relative of the Red Imported Fire Ant, Solenopsis invicta. You're already doing some of the most effective things: Amdro was developed specifically to target S. invicta (or RIFA, as it's sometimes called in the invasive species literature). It works best if you pour about 1/4 cup directly onto the mounds, and re-treat every 2-3 weeks. In general, poisoned baits usually kill at most about 90% of the colony, so re-treatment is essential. Boiling water, as you said, is also great when you can find the colonies. Just don't pour it over the Amdro! It doesn't work when wet!
The problem is, unless you and your family live on a 1,000-acre ranch, miles away from town, surrounded by a moat and a flying-ant-proof fence, you'll always risk re-infestation from the surrounding area. Therefore, the only further advice I have is to get organized with your community. It might make sense to bring this problem up with your neighbors, at your children's schools, and any local organizations you're involved with. The "School of Ants" is a citizen-science project that would be a fantastic way to gather information about where other colonies of these ants occur in your area...and the students might even learn a thing or two about the biology and ecology of ants!
One critical bit of information you can get from collaborating with the folks at "School of Ants," or other experts, is a positive identification of these specimens. Solenopsis invicta and Solenopsis xyloni are difficult to tell apart from pictures, but one is a native ant that can be a nuisance, and one is an invasive ant that costs the USA more six billion dollars a year to control nation-wide. More information on Solenopsis invicta, and some advice about distinguishing it from related species, can be found on this excellent site.
Either way, you have the opportunity to raise awareness in your community about ants, so that you can more effectively solve the problem you have now, and be prepared for future ant invasions.
Jesse Czekanski-Moir & the AntAsk Team