Saturday, May 21, 2011

Formica pergandei Give a Head Start

I have two Formica colonies started from queens last year. One is Formica pallidefulva and she started laying eggs maybe a month and a half to two months ago. She's already got some fresh workers born for the year and it looks like the colony will continue to grow well into the autumn. The other colony I have is interesting though, Formica pergandei.

Formica pergandei is a social parasite of other Formica species. That is F. pergandei queens can't start a colony on their own. They have to invade established colonies of hosts and replace it's resident queen, usually by assassination and stealing the colony odor by rolling in the queen's juices, etc... so the host workers don't turn on here.

This picture was taken yesterday. Note the eggs scattered about as well the large clutch the worker in the middle is holding. As a social parasite she started laying eggs about a month later than the host species.

She may produce workers but sometimes social parasites are so dependent to their host species that they're required for their survival. The trouble is the F. pergandei queen had to replace the F. pallidefulva queen in order to start her colony, so they're eventually going to run out of host workers. 
F. pergandei colonies get around this by raiding established host colonies for brood. Occasionally I believe host colonies are out right overrun by the F. pergandei as they move their entire nest into the new location. It's a vicious cycle but at least the F. pergandei are giving their hosts a chance to get a head start. Come summer though the F. pergandei will be born and raids will begin.