Tuesday, July 15, 2008

Desert Boy and Henry Learn about Harvester Ants

While we were taking a walk the other day, I noticed the large number of harvester ant mounds among the bushes. Desert Boy and Henry went over to investigate.
Harvester ant mounds are easily distinguished, with a small hill of sand and gravel rising from the ground, sometimes as much as two feet high. Harvester ants belong to the genus Pogonomyrmex, and their predilection to make these mounds make them easy to identify. In our area we have more than 30 species of ants, but just two are Pogonomyrmex ants.
Desert Boy thought it was great to take a look, but because harvester ants have an extremely toxic poison, it's not good for him to get too close. Harvester ants are some of the most venomous animals in the world, with a venom 3 to 12 times as strong as a bee. Or in other words, one ant bite is equivalent to up to 12 bee stings. Ouch! Fortunately harvester ants have tiny mouths and don't bite often, as long as you stay out of their colony.
Henry takes a look at the harvester ant mound. The ants have dug deep into the earth so that they can take the seeds they find. In addition to seeds, they also eat small insects and other invertebrates. In turn they are eaten by horned lizards and some birds.
Here we can see ants coming and going out of the mound entrance. They turn over and aerate as much soil as earthworms.
The ants will stay inside the mound during the hottest part of the day. Then they go out to find seeds and insects and bring them back.
Here's a closeup of a harvester ant. It's a little blurry because the ants move fast! By the way, the head is the square end with the antennae sticking out.
One of the things that caught my eye as I walked past several harvester ant mounds was the entrance. It was always on the south or east side of the mound. One hypothesis about this entrance location is that it warms up faster in the morning than if it was located on the north or west side.
Harvester ants clear the vegetation directly around the mound. Although it might be tempting to try and kill the harvester ants, they are a natural part of the ecosystem, found throughout the western United States. In Texas and Arizona, the red imported fire ant is slowly taking over harvester ant territory, and these fire ants are much worse for humans than the fairly benign harvester ants.
One ant in this photo is carrying part of a plant that is bigger than himself. Ant watching turns out to be a fun sport: which ant is carrying the biggest thing? Which ants go in straight directions and which ones meander?
Desert Boy is enjoying his experience as an ant watcher. Ready to join him?

7 comments:

Andrew said...

Are they in Colorado as well? I thought I saw some at the Great Sand Dunes!

flatbow said...

Desert Boy will enjoy ant watching even more once he learns how to burn them with a magnifying glass!

Sarah said...

Hey, he's got shoes on! That's hardly sporting for the ants.


:)

I Am Woody said...

And I thought fire ants were bad!!

Dessert Survivor said...

Are you sure it is the bite that is poisonous and not the sting? With fire ants it is the sting that is the problem.

(That is dessert, not desert)

Anonymous said...

Other than that, an excellent post though, and I'm glad to see a nice showing respect for harvester ants, a beneficial desert species.

Desert Survivor said...

WFReptileRescue, thanks for taking the time to comment with those corrections! Ants are so fascinating once you spend a little time learning about them.

Cheers-Desert Survivor

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