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October 12, 2020

Have a thick skin when it comes to Insidious Flower Bugs

Tim Gibb, Insect Diagnostician, Department of Entomology, Purdue University

‘Big bite for such a little bugger!’ is most often the comment made by residents of the state who experience the bite of the Insidious Flower Bug.  In most cases one might feel the bite on bare skin during a warm day in mid to late fall before they are actually seen.  Upon close inspection, one might see a tiny black dot only slightly larger than the period at the end of this sentence. Under magnification they resemble chinch bugs, 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 and 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. 

Click image to enlarge
Insidious Flower bug biting skin. Insidious Flower bug biting skin.
Size of bug compared to finger tip. Size of bug compared to finger tip. Photo credit: John Obermeyer, Purdue Entomology


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 bugs 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.  Soybeans and corn often harbor these bugs and may be the reason for high insidious flower bug populations, in agricultural areas.  These may be a real pain right now but have patience and a thick skin.  They will be gone soon enough!

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