Harvester Ant Nest Midden

During a quick hike through South Mountain Park in Phoenix, Arizona yesterday, I spotted a Messor Pogonomyrmex rugosus harvester ant mound.

messor-nest

The refuse or midden pile was covered with a fluffy material.

chaff-messor-nest

The ants apparently have been collecting the seeds of this plant, and discarding the seed coats.

creosote

It is a common plant in the Sonoran desert. Do you know what it is?

creosote-with-bee

The plant is a food source to a range of insects as well as Messor harvester ants, including more than 20 species of bees.

creosote2

It is the common creosote bush, Larrea tridentata.

The midden piles of harvester ants, as with many other types of ants, are known to improve the nutrient levels in the soil in the immediate area.

Tomorrow I will post more about Messor harvester ants.

Hum, now that I think about it, I wonder if "midden piles" is redundant, because midden is a trash heap. Anyone out there help me out on this?

Edit:  Thanks to Alex Wild for pointing out that these ants were Pogonomyrmex rugosus, not Messor.

Edit: Here's a photo of Pogonomyrmex rugosus.

For more information, try:

Desert Harvester Ant, Messor pergandei

Dale Ward has some videos of Messor pergandei in action, as well as more information

More about cresote bush and the Zygophyllaceae (caltrop family) at the Arizona-Sonora Desert Museum

4 thoughts on “Harvester Ant Nest Midden

  1. M. White

    Out hiking this afternoon near Telegraph Pass in Yuma and noted lots of forage ants actively taking seed heads from creosote bush back to the mounds.

    Later this summer the middens will appear outside mounds.

  2. Roberta

    Post author

    Hasn't the weather been great for hiking? I got out for a few minutes this morning.

    Do you know what kind of ants you saw?

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