P&PDL Picture of the Week for
September 21, 2009

Bugs in Bad Moods

Tim Gibb, Insect Diagnostician, Entomology Department, Purdue University

During the late summer, small insects that are otherwise innocuous can become troublesome.  These insects just seem to be in a foul mood and are intent on sharing a bit of their misery with humans before the first freeze of the season takes them out. I can think of no other plausible reason for them to be biting or more accurately pinching people.  They do not take blood, inject toxins or venom, or seldom even break skin but their painful pinch sure seems out of proportion with their size.

The culprits come from several different families of insects, including lady beetles, insidious flower bugs, and hackberry lace bugs. 

These insects are well mannered throughout most of the summer.  They occur in fields, woodlands, gardens and landscapes where two of the three are beneficial because they feed on other small insects such as aphids that are potential pests of plants. In the late summer, these insects tend to congregate around residential areas and when temperatures are really warm, they begin the unpleasant behavior of biting humans.

People differ in their response to these bites. Some people have no reaction to the bite, but others have bites that swell like a mosquito bite or turn red.

Control of these fall time biting bugs is not practical. Repellents are generally not effective, although some people swear that applying baby oil or suntan oil protect them.  Certainly, wearing long sleeves and pants keeps them from biting otherwise exposed arms and legs.  Our best advice, If you do not have an electronic ‘biting bug mood sensor’, is to simply be aware of where and when they are active and avoiding those times and places. 

Click image to enlarge

Lace bug on sycamore leaf

Asian lady beetle

Insidious flower bug (Minute pirate beetle)

Hackberry lace bugs

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service