Not all ants are the same. Recently I went to a house where a family had an infestation of ants. Two companies gave them prices on the phone without knowing what they are and when they saw them, they couldn’t identify them. They suggested spraying and baits. They called me and I went out there and I didn’t recognize the species of ants. I knew they were big-headed ants (genus Pheidole), but I couldn’t tell which species without putting them under a microscope. There are 33 species of big-headed ants in NM and they have different habits, different size colonies and different number of queens. You have to know specifically which species you are dealing with if you want to control them. I took some samples home and examined them under a microscope and it was clear from the shape and size of the antennae, that they are Pheidole desertorum. This species has very large colonies and usually goes under large boulders when winter approaches. They are not common house pests, but in this case they went under the person’s house. They needed water, so they came into the house via the expansion joints and kept getting into the sink. They tried some store bought baits and the ants ignored them and they didn’t want pesticides along the baseboards because of their dogs.
I told them that baits would not work very well with these ants. They feed on seeds. They are dimorphic, meaning they have minor workers and major workers. The minor workers gather seeds and the major workers, with their large jaws, break the seeds open. They won’t take a bait unless it is in a seed-like form. The only bait I am aware of that may work with these ants is Niban Bait in fine grade and is made from boric acid. This bait is only available online. I recommended the people controls the ants themselves by spraying along the baseboards with a cedar oil product. There are several brands. One is Wondercide. This will only last a week or so, but it is absolutely safe for their dogs. I also suggested they fill their sinks with a few inches of water and a little soap. If the ants wanted water they would go into the sink, which is what they did. They caught hundreds of ants in the sink this way. I also recommended that they put some diatomaceous earth behind or under the baseboards wherever it was possible. Diatomaceous earth will last a long time. It would not be practical or possible to seal all the expansion joints around the perimeter of the slab of the house. I got a call and they told me the ants are totally under control now and they are happy. They see a few here and there, but they almost eliminated them without using any pesticides.
There are approximately 225 species of ants in New Mexico. That is more species of ants than there is in all of Europe. Of course the vast majority of them never enter homes and you will never see them. However there are a few species that don’t normally enter homes, but will occasionally and they need to be properly identified before a treatment is performed. Some of these ants are so obscure they don’t have common names. When I worked on UNM campus, a species of ant in the genus Forelius occasionally found their way into a building. I recognized them, so was able to treat for them. They resemble Argentine ants, but you need a microscope to tell them apart. The hairs on the clypeus are shorter on Forelius than on Argentine ants. Their habits are completely different, so treating for Argentine ants will not work for Forelius. Another ant that occasionally enters home are in the genus Liometopum. They are difficult to control if you don’t know their biology and feeding habits. Ants in the genus Paratrechina are also occasional household pests. Ants in the genus Lasius are often found in homes along the river and ants in the genus Formica are occasional pests. Formica ants are commonly known as field ants, but they are rarely found in fields. There are 56 species of ants in the genus Formica and it is important to know which species you have in order to control them as they all have different habits and different size colonies as the big-headed ants to. There is more to controlling ants than identifying them as “sugar ants”, spraying the baseboards and putting out toxic bait stations. Make sure anyone you use to control ants is competent in myrmecology and can properly identify them. In most cases you can control the ants yourself as long as you get them identified. I can help anyone identify ants in NM or anywhere in the country.
My email address is firstname.lastname@example.org. I have a handbook available on the identification and control of household ants.