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

Ant Structures With GPS Addresses

Foresters are set to log the ancient Holystone Forest, in Northumberland, England. But first they need to locate and save a few homes located in the forest. Are these structures human dwellings? No, they are giant ant mounds.

The northern, or hairy wood ants  (Formica lugubris) build towering mounds out of pine needles, from three to seven feet tall. The nests act as solar collectors and heaters, allowing wood ants to live in places too cold for most other ants. In addition, the large black and red workers sometimes bask in the sun to warm up and then move underground to act as living heat radiators.

wood-ant-mound
Smaller wood ant mound from Switzerland

The hairy wood ants that build the mounds are now endangered, and every effort is being to made to protect them. Naturalists located of 69 mounds, which they mapped and gave GPS coordinates. Hopefully, the maps will help the loggers avoid getting too close.

For photographs and more information, see:
Guardian.co.uk has a story: Giant ants’ nests given special building protection

York Dales Country News story:  GPS used to protect ant ‘skyscrapers’

For photos and more information, see BBC – Potter ponders giant anthill

Edit:  And for children, see The Ant’s Nest book review at Simply Science.

Ant Nests Under Rocks

Recently, during International Rock Flipping Day, several of the participants found ants under rocks. See for example, Fertanish Chatter found some golden yellow ants, and Just Playin’ Around found black ants with larvae and pupae. Here is a list of all the Rock Flipping participants.

When I flipped a rock in northern Arizona last week, I found these ants with the eggs and larvae.

ants-under-rocks

Why do you think ants live under rocks? I have noticed they often have piles of eggs, larvae and pupae under rocks, particularly in cold climates. Do you think perhaps the rocks warm the ground and they are using them as heaters to keep the young ants warm?

Because they often live underground, we might not give as much thought to the nests constructed by ants. Dr. Walter Tschinkel has modified an older technique for looking at the structure of ant nests by pouring dental plaster into the tunnels, allowing it to dry and then digging up the nest, giving a negative-space impression of some truly impressive ant nests.

Dr. Walter Tschinkel’s Ant Castles can be found at the Florida State University. He’s says that the ants can build the huge one at the bottom in just five days!