Hedgehog Gall

Subject: Strange Egg Sac
Location: Effingham, IL
September 10, 2016 7:19 pm
I found this strange (what I believe is an) egg sac on a fallen leaf in Effingham, IL. I know you identify insects. Are you able to identify their eggs as well? Assuming this is an insect egg… Thanks!
Signature: Best, Jennifer

Spiny Oak Leaf Gall
Hedgehog Gall

Dear Jennifer,
This is a Gall, a growth appearing on a plant that might be caused by an insect, other arthropod or even an injury.  We found a very similar image on the Blue Jay Barrens blog, but the only information is:  “The oak leaves are developing some wonderful galls. I’m not sure how large these pea sized growths will eventually become.”  We found an image on Field Biology in Southeastern Ohio with the information:  “Spiny Hedgehog Galls. The yellow gum drop covered in red hairs makes this wasp
Acraspis erinacei. ”  Another similar image is on the Springfield Plateau blog and the name Hedgehog Gall is used.  Hedgehog Gall is also the name used on BugGuide and according to BugGuide:  “Forms galls on white oak (Quercus alba). The sexual generation forms galls on the buds, and the agamic generation forms the distinctive ‘hedgehog’ galls (ellipsoid, up to 13 mm in diameter, covered with red hairs, with 3-5 larval cells inside) on leaves. Females emerge from the leaf galls in the fall (October-December) and crawl to the buds to oviposit. The resulting gall is a thin-walled blister on the inner face of a bud scale, appearing as the buds start to open in the spring.”

Hi Daniel,
Thank you so much for sharing!  How incredibly interesting.  Nature is amazing.

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