The Purdue Plant and Pest Diagnostic Laboratory

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October 12, 2011

Tiny Little Black Bugs that Deliver a Big Bite

Timothy Gibb, IPM Specialist, Department of Entomology, Purdue University

Some say they feel a sharp bite on arms or legs but then have to search to find the cause. What they find is a very tiny black bug, almost too small to cause such a bite. Rest assured, however, that these are the culprits. Think of them as - a big bite in a small package. These bugs (insidious flower bugs) are becoming quite a nuisance on warm afternoons as of late and are expected to continue into the fall.

Insidious flower bugs are 2X larger than the period at the end of this sentence, broadly oval in shape, and black with whitish or silver markings on the back. Insidious flower bugs can fly and often make their way through window screens to provide equal irritation to people inside homes as outside. Why they bite is still a bit of a mystery. However, we know that they live up to their name "insidious" and bite when it is warm out. We have also found that they usually bite people who are perspiring slightly. They do not take blood or inject any saliva so in most cases, their bite is not particularly serious to most people. However, it is certainly annoying especially considering the small size of these bugs. Some people react more to the bite than others and may experience localized swelling like a mosquito bite. Others experience the pain but see no reactions at all.

Not much can be done about these nuisance pests. Insect repellents can be used and will probably offer some protection but not complete. Covering bare skin will prevent them from biting.

Remember that during the majority of the year, these are beneficial predators because they feed on small insects and mites or on their eggs. Spider mites, aphids, and thrips are particularly attractive to these bugs. For that reason, general insecticides should not be used against these insects.

In years past we have experienced localized outbreaks of these insects and we have found that with the first frost they will be gone. Our advice now has not changed - have patience and a thick skin. They will be gone soon enough!

Click image to enlarge

Insidious flower bug (Photo credit: Ho Jung Yoo)

Insidious flower bug: Orius insidiosus (Photo credit: John Ruberson, U. Georgia,



Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service