	AllExperts > Entomology (Study of Bugs)
	Search

About Jack DeAngelis
Expertise
I can answer questions in any area of entomology (study of insects, spiders, mites, ticks, and other terrestrial arthropods). Contact me about home and garden insects, insects that bite and sting, and insects that damage homes such as carpenter ants and termites.

Experience
20 years as university extension entomologist, now retired; currently publish a website about home and garden insects.

Publications
see www.livingwithbugs.com/resume.html

Education/Credentials
Ph.D. in Entomology

You are here: Experts > Science > Insects/Spiders > Entomology (Study of Bugs) > Window stains left by dead house flies

Entomology (Study of Bugs) - Window stains left by dead house flies

Expert: Jack DeAngelis - 11/6/2009

Question
My neighbors and I are curious - what causes the stains left on a glass window when a fly dies while hanging on the window? Is it from some kind of gas emitted from the dead fly? The spots seem to develop fairly quickly around the dead body and seem to surround the area where the dead fly is left stuck to the glass. Note this is a fly that dies on its own - not one we squished!!

Answer
Shirley,

This is a fungus (mold) and it was responsible for killing the fly. These fungi are harmless to us but deadly to insects. When the insect dies the fungus grows out of the body. Some of these fungi are even used to control insects, in the same way that insecticides are used. If you are curious google "microbial insecticides".

Jack DeAngelis
http://www.livingwithbugs.com

Ask a Question