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Photo#701135
Wheel Bug Abdominal Protrusion - Arilus cristatus

Wheel Bug Abdominal Protrusion - Arilus cristatus
Bethel Park, Allegheny County, Pennsylvania, USA
August 21, 2012
This was the largest Wheel Bug (Arilus cristatus) I have ever seen in my life (female?) When disturbed, it extruded an orange glandular organ of some sort. I was reminded of osmeterium in swallowtail caterpillars. Does anyone know anything about this? I've never noticed one do this before. Can't say I noticed any smell, but it was after a rain and a buddleia was competing with scent. Thanks!

Images of this individual: tag all
Wheel Bug Abdominal Protrusion - Arilus cristatus Wheel Bug Abdominal Protrusion - Arilus cristatus

They're referred to as
"scent sacs" in Wikipedia and in this article.

Moved
Moved from ID Request. I've seen the extrusion once while handling one of these and I assumed it was a defensive reaction. But I don't know for sure.

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