What is This?
July 8, 2010
Dear Bugman,
Recently, I went hiking to an old monastery in Turin, Italy. The trail was punctuated by large cement crosses that had something to do with the myth of the Stations of the Cross. Worried about having a Jesus overdose, we sought an alternate route. Along the way, we came across this deformed tree. Thinking it was perhaps the work of Satan, we went back to the JC trail.
I am not convinced that these odd thorny growths are from the devil’s hand. Seems he could do a lot better than this. I suspect it’s a bug!
Any ideas?
Godless Hiker
Turin Italy

Grape Tube Gallmakers

Dear Godless Hiker,
These odd thorny growths appear have been produced by the Grape Tube Gallmaker,
Cecidomyia viticola, a species of Midge.  The plant appears to be a wild grape which would support our identification.  We ran a similar photo from Alabama in 2008.  Galls are generally considered to be growths on plants that may be caused by insects including wasps and flies, or by mites or other arthropods.  BugGuide indicates: “Gall insects (and mites) are usually highly specific about what kind of plants they use, and even what part of the plant. To maximize your chances of getting a gall identified, record the plant species (include photos of the leaves, flowers, fruits, etc. if you’re not sure), and if it’s a leaf gall, note the position on the leaf (if it’s not obvious from the photo): upper side or underside; midrib, side vein, or somewhere else. Also note whether or not the gall is detachable, the size of the gall, and anything else distinctive about it that may not be clear in the photo. With oaks in particular, which are hosts for hundreds of kinds of galls, every little detail can help to narrow down the options.”

Grape Tube Gallmakers

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