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.

Toothbrush Ants


This week my son and I have been watching a toothbrush. No, we haven’t gone bonkers. This does have something to do with ants.

You see, we saw this post about an unusual Ant-traction. It seems that a certain type of ant likes the rubbery buttons Colgate toothbrushes. Go check it out. Here’s a link to the original post, as well.

The first thing we wondered, of course, was whether this is a prank or hoax. I think you could get the same effect by rubbing a little sugar water or honey on the brush.

We bought a toothbrush to check it out. So far our fire ants, Solenopsis xyloni, could care less about the toothbrush. But that doesn’t mean the effect isn’t real. It could be that the rubbery bit contains a pheromone specific to one or a few closely-related species of ants. We are going to continue our experiments.

If there turns out to be something to this, it won’t be the first time humans have inadvertently produced a product that mimics an insect pheromone. One classic example is the finding that termites of the species Reticulotermes flavipes will follow an ink trail drawn by a certain type of pen. (See for example, this experiment).

If you’d like to learn more, here is a video showing EO Wilson explaining some of the basics of pheromones and other chemical signals in ants:

We’ll let you know if we get any ants to react.
And please let us know if you try this experiment, what your results were, and what kinds of ants you used.