Western Thatching Ant - ever hear of an ant mound?

Up to 40,000 western thatching ants make up a single colony, and they build quite the ant hill.

Formica obscuripes, the western thatching ant, has a red head and black thorax and body.  While a red and black ant is nothing new, the fact that this species' head is the only red part makes it somewhat unique, certainly in this part of the world anyway.  If that wasn't enough, you can always look for what it calls home, a large, dome-shaped mound made of organic material.  I usually see them made of coniferous needles.  If you want to see a good example of one, click here.  Mounds may be up to a meter high, although the ones I have witnessed have been under a foot high.

Ants, like most of their species, are foragers, heading out of their nests to collect food or building material.  The building material depends largely upon what is available in the area.  Soil, from the burrows, and plant debris are placed around the colony entrance.  A secondary nest may be constructed near plants that host aphids and other homopterans that create honeydew.  The ants "farm" these insects; it is a form of mutualism where the aphids get protection and the ants get the sugary nectar they produce.  I wrote a blog on the subject which is available here.

An unusual fact about western thatching ants is that a colony may have more than one queen laying eggs.  This condition, called polygyny (how many words do you know with three y's?), may have up to 200 queens in a single colony.  Normally, there are only a dozen or so though.  Secondary nests may have their own queens, but ants may travel between colonies without the risk of being killed.

I have, on occasion, dug into the mound of a thatching ant colony.  My efforts were met with the immediate inundation of very irritated insects.  I once made the mistake of unwittingly standing on an ant mound and found them crawling up my legs - no doubt with evil intentions.  They are a remarkable species.  Good to observe, from a distance, that is.

Thanks for reading.

Eric Svendsen     www.ericspix.com