Saturday, April 3, 2010

Hackberry Petiole Gall Psyllid

Pachypsylla venusta (Osten Sacken)

March 15th was one of those unseasonably warm days.  A tiny insect that looked like a cicada (above) was one of hundreds swarming the Chippewa River State Trail.  I didn't get a good look until one landed on my thumb.  It looked like it could suck the guts out of me.  (It didn't).

I had no idea what it might be until today, when I took a photo of this hackberry sapling full of dried galls.  I wanted to see what the insect that made it looks like.  That's how I discovered the identity of my March 15 mystery creature:  the hackberry petiole gall psyllid (also known as jumping plant lice - they suck sap from leaves and stems).   This psyllid species forms woody galls on leaf petioles. 

Infested leaves do not fall from the trees and heavily infested trees are recognizable during the winter by the presence of the dead leaves. The adults emerge in the spring after the nymph cuta its way out of the woody gall.   While they apparently do not harm the hackberry trees, these old galls can remain on the trees for years.

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