What are these small black ants in my room? (Leah, Las Cruses, New Mexico, USA)

Dear AntAsk Team,

I live in southern New Mexico, (Las Cruces) and I have an odd little infestation of ants. Only in my bedroom, only in one little spot. I don't know how or where they are getting in, because they don't travel in a line. They are small and black. I did my own research, and can't decide if they are crazy ants or little black ants. Is one or the other more common here? How do I get rid of them? I honestly don't care if they are outside, since I can't find their nest anyways, but I don't want them in my room. I don't have a magnifying glass, so I can't see their nodes or antennae.

Please help me figure it out! Some are pretty tiny, but I'd say one out of five of them are significantly bigger, yet still small. I only ever get between 12 and 20 at a time, and only in one small spot in my bedroom. Can't find nests outside, can't find a line....But they are starting to take an interest in exploring my bed, and I am NOT ok with that, lol.

Thanks, Leah

Dear Leah,

Thanks for your question! Your observation that some workers are significantly bigger that others is very useful: there are some ants that have a worker caste that comes in two distinct sizes--we call those species dimorphic. Pheidole is a very common genus in many different habitats in North America that is dimorphic. Members of this genus are nicknamed "Big-Headed Ants," because the large worker caste have enormous heads. See for yourself!
Although it is glaringly obvious under a microscope, their big heads should be visible with the naked eye (if you look very closely, and if you have good eyes).

If the heads of the larger ants don't seem ridiculously huge, then it is likely that you have a member of the genus Monomorium. The members of this genus usually have workers that vary continuously in size, from large to small, but they usually travel slowly in distinct lines.

Crazy ants (this name usually refers to ants of the genus Paratrechina or Nylanderia) don't have workers of multiple sizes. However, if a worker drinks a lot of sugar water (or other sweet substance, or just plain water), the last section of their body (gaster) will become noticeably larger than other parts. So do your ants have big heads or big gasters?

Other common and very small, black ants include some members of the genera Solenopsis and Tapinoma, but these ants generally don't have works of different sizes.

As for how to get rid of ants in your room, we have some general tips in a different post, here. Please email us back if you don't have any luck, and we'll try and offer you some more advice.

Jesse Czekanski-Moir & the AntAsk Team

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