Wednesday, April 27, 2011

The cuddly alfalfa weevil

Note the proboscis and dark median stripes characteristic
of the alfalfa weevil.
Each year in pest control brings a few surprises.  This year's early surprise is a small outdoor insect known as the alfalfa weevil, Hypera postica. The alfalfa weevil is a small, 3/16-inch (5 mm) long, brownish-grey weevil with a darker brown band down the back. It normally spends the winter as an adult at the base of clover or alfalfa plants, or under leaves or other debris outdoors.

Now weevils are pretty interesting insects, with some of the, if not beautiful, most bizarre-looking faces and life styles among the beetles. Only a few weevils ever become pests--at least indoors. The rice and granary weevils are probably two of the most common, and can be found associated with stored rice and whole grains.

In the twenty years that I've been answering phone calls from county extension agents and citizens I don't recall receiving any complaints about alfalfa weevils invading homes or structures.  This year must be different.  Over the past few weeks I've had several calls and emails about alfalfa weevils (1) being found indoors, (2) being found in large numbers on the outside of homes, and (3) being found in beds (three complaints!). 

OK. There is no good reason why alfalfa weevils should be interested in a bed--unless they just like to cuddle.  Alfalfa weevils do not bite and certainly are not blood suckers.  I can only guess that these insects must be good at climbing up folds of fabric hanging down from a bed. Also, bedrooms and beds tend to be located at the exterior perimeter walls of home.  And certainly one of the easiest places to spot these small gray weevils would be on white bed linens.

Although I can't confirm that alfalfa weevils fly, it's possible that these insects are being drawn to external lighting, and subsequently indoors.  If you are servicing a home that is under siege from alfalfa weevils, standard recommendations for control of occasional invaders should apply: (1) reduce or eliminate outdoor lighting, especially lights that shine or doorways or shine directly on the sides of the home; (2) seal doors, windows, and cracks or gaps in walls, soffits or foundations; and (3) apply a residual insecticide to foundation perimeters and around potential entry points into the structure.  Indoor pesticide applications, including aerosol bombs, are not recommended.


Brian said...

That's a very cool looking bug!

Jamie Delzell said...

Just found one in my bed!! Had to look it up to see what it was and stumbled upon this. Made me feel better to know it wasn't anything crazy, like bed bugs.