Solenopsis xyloni Stores Spurge Seeds

Last week I flipped over a rock about six inches square and found this:


Okay, it doesn’t look like much until you zoom in closer.


The grayish-mound is a solid mat of oval, wrinkly seeds. Apparently they had been gathered and stored by the Southern fire ants (Solenopsis xyloni) you see running around. The ants were in full defensive mode.

The seeds were both on the ground and on the underside of the rock, so there was quite a mass of them.




Seeing the seeds reminded me of an earlier time (above photograph) I had found a similar cache of seeds under a rock . At the time I didn’t know what plant they were from, but now I have figured it out.

These seeds are from a type of ground spurge, Chamaesyce prostrata. Another common name is sandmat. (See post about Southern fire ants and sandmat).

The University of Arizona has an illustration of the plant in their older weed manual under the name Groundfig Spurge, Euphorbia prostrata. See the seed labeled “d” in the illustration?

A quick search of the internet revealed the UC IPM website states “Weed seeds, particularly spurge, may attract the ants away from the bait…” This statement is referring to Southern fire ants in almond groves.

Seems like there might be something worth investigating going on here.

Have you ever seen Southern fire ants with seed caches? What kinds of seeds did you find in them?

Dogwood Flower Community

Sometimes we get so used to seeing ants visiting extrafloral nectaries, it seems unexpected to see them visiting regular floral nectaries.


Take this shrubby dogwood flower (probably gray dogwood, Cornus racemosa). The nectaries are the creamy yellow bands at the base of the female part of the flower (the pistil or carpel) in the center.



Formica workers seemed to be visiting the plants most frequently, although other ants were in the area.


Ants weren’t the only insects attracted to the nectaries of the dogwood flowers.


Along with the usual wasps, flies and bees, there were also more unusual true bugs and beetles.


A number of the smaller butterflies stopped by, including hairstreaks and blues.

It turns out azure butterflies in particular are attracted to these types of dogwoods and lay their eggs on them. What happens next? Of course, the ants tend the azure caterpillars! Nature Posts blog has an incredible series of photographs and videos of ants tending azure butterfly caterpillars.

Interested in planting a garden for ants or butterflies? You might want to consider planting some of the dogwoods (Cornus sp.)

Have you ever seen azure caterpillars on dogwoods? I am definitely going to be looking from now on.


Body Shop For Ants?

Have you ever been on the quest for something and discovered something else entirely?

Take my pursuit to capture a “calendar-perfect” photograph of ants visiting peony buds. People have known that ants tend extrafloral nectaries on peony buds for a long time. It is one place that you are sure to find ants sitting relatively still (for ants) out in the open. Taking some colorful photographs of ants posing on peony buds seemed much easier than trying to capture one scurrying on the ground.


As I was looking through the shots, I began to notice something else.


It was subtle at first, but it’s there if you look for it.


The one on the left will give you a big hint.


Here’s one on a peony flower.


See it now?



It seems like ants on peonies have more than their share of dents and missing body parts. If they were cars, you’d be sending them to the body shop.

I think it is conventional wisdom that foragers are the older ants in the colony and that older ants are probably more likely to be beat up a bit. It is possible, however, that tending peony buds is extra risky. What do you think?

Do you have a photograph of a “dented” ant? Leave us a link in the comments or share it on our Facebook page (No fair creating the dents yourself).