Friday, August 7, 2009

Ant Cocoons

Some ants, such as the Allegheny Mound Ant, Formica exsectoides, create a cocoon in which to pupate. After the adults emerge, the spent cocoons are deposited outside the mound.

I don’t know if there is a strategy for used cocoon distribution, but the cocoons seem to be initially scattered randomly about the mound. In typical ant fashion, the ant will carry the cocoon remains to a place of disposal and carefully arrange it before going back inside the mound.

Wind and rain will gradually move the cocoons down the slope where they accumulate at the base of the mound. The ants have just started bringing cocoons to the surface. Within the next few days I expect the mounds to be nearly covered with this litter.

During cocoon cleanup time, the ants open new entrances near the top of the mound. These new openings must make trash removal activities more efficient.

This particular mound is three feet high and about eight feet across. The colony responsible for this mound could easily contain more than 400,000 individuals. If you see one of these mounds in the next couple of weeks, take a look to see if there are cocoons. Remember to use caution in your observations. These ants are not shy about climbing up and chewing on your ankles.

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