Forelius mccooki ants

We have some amazing ants in Arizona.

People always comment on the tiny ants that run rapidly along sidewalks in great numbers.

Here’s a very amateur video in real time, to give you an idea of their speed at about 90 degrees F. I particularly enjoy the traffic noises in the second part. I thought the revving sounds were quite appropriate. 🙂

Based on their behavior, I figured they were genus Forelius.


These particular ants are apparently Forelius mcccooki rather than the common Forelius pruinosus, based on the hairs on their antennal scapes, etc. Dale Ward has a page about Forelius pruinosus in Phoenix. Alex Wild has photographs of F. mccooki.


The fast little ants stretched the limits of my photography skills.

forelius -2


Here I tried the doubler.


One thing I noticed while watching is that the F. mccooki workers seem to have greater than usual amount of color variation.

For most ants, if you open a colony you will see lighter than usual individuals. These are the newly emerged callows. Their color will darken over time. Generally the callows work inside the nest.

Seeing the mix of light and dark colors in the foragers is less common. Alex Wild has a photograph of color variation in Forelius pruinosus workers.

What’s going on? First of all, Forelius exoskeletons are easy to see through, as Dale Ward shows.

Secondly, the colonies have multiple queens and could be genetically diverse.

I have another idea, but without a lab or lab equipment, I’ll have to wait on that one.

Continuing Toothbrush Experiment:

What I can test is whether Forelius ants are attracted to a toothbrush. When I put the toothbrush into a foraging trail, no response.


I’ll keep carrying the toothbrush.

2 Replies to “Forelius mccooki ants”

  1. Miles sez: I like the toothbrush project. I want to see the toothbrush covered in ants 🙂

    Great blog, Roberta! Just looked at the first post here – wow! Great to see the expression of your passion 🙂 Inspiring and educational.


  2. Well, I don’t know about educational LOL!

    Miles: We’ll see about getting those ants on the toothbrush. I forgot to take it camping this weekend, but I’m definitely taking it when we go back east on vacation.

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