Monday, February 14, 2011

Prime Weather for Paper Wasps

You aren't the only one heading outside to enjoy the beautiful weather... female paper wasps have started leaving their winter homes and may soon be seen swarming yours!
Paper wasps (Polistes spp.) eat a lot of insects and are usually considered beneficial to the landscape.  They are best known for their open, grey paper nests built under an open porch ceiling, window sill, or any type of overhang.  During their nesting phases, paper wasps can be defensive and are likely to sting you if you disturb their nests.  
During the cool/ cold times of the year, when their are no nests or young to protect, paper wasps show types of swarming behavior.  In the fall, this behavior is connected with mating.  Male wasps look for the best place to "hang out" and attract the females.  Dozens or even hundreds might be seen around the upper stories of buildings and other tall towers.  Males locate a good perch, camp out, and release odors (pheromones) to attract the pretty female wasps.  Some time after mating, the males die and the females seek a shelter for winter. 

During winter and early spring, on any warm day (like the one's we've been seeing this week!), these wasps become active.  If their shelter is inside a wall, chimney, or vent, they may follow the light into the inside of a structure rather than moving outside. The only risk is unknowingly coming into contact with the wasp and being stung. The future queens become active on warm days and start flying around, however they are not particularly defensive and are unlikely to attack.  This flying behavior disappears at the end of the day when temperatures drop and the wasps resettle.  
The best management and control of these wasps indoors is a rolled-up newspaper.  Aerosol pesticides work, but they cost money and aren't particularly necessary if you are able to whack the wasps with a paper or fly swatter.  

For more information on Paper Wasps click the link below:

Special Thanks to Steve Bambara and Michael Waldvogel for this great Insect Note!