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Gall on oak tree ? - Druon quercuslanigerum

Gall on oak tree ? - Druon quercuslanigerum
Manteca, San joaquin County, California, USA
September 17, 2007
Size: varying sizes up to 1/2 "
I found these ( galls ? ) on only 1 young Oak tree in a line of 6 . These puff balls were all over the underside of the leaves . Some were linked together and resembled fuzzy caterpillars and some were single . The only bug that I found near them was a couple fireflys that looked interested in searching around them . Do Wasps cause galls ? Has anyone seen this kind of gall , and which Wasp is responsible ? Thanks for any comments , sincerely Beth

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Gall on oak tree ? - Druon quercuslanigerum Gall on oak tree ? - Druon quercuslanigerum Gall on oak tree ? Gall on oak tree ?

Moved from Andricus laniger.
Current name is Andricus quercuslanigera, per Kathy Schick.

I had a lot of adults emerge from the galls from these oaks earlier this year ... just got around to posting a photo of one of them here:

Moved from Gall Wasps.

likely Andricus laniger
Following up on the discussion on this page, these galls are likely caused by the cynipid wasp Andricus laniger, based on Lewis Weld's Cynipid Galls of the Eastern United States (1959). Of the eight leaf galls listed on Quercus virginiana, Andricus laniger is the only one that is as woolly as these are and occurs on the underside midrib vein. The description in Felt's Plant Galls and Gall Makers (1940) agrees with Weld's.

I'm reluctant to move these to a species page yet because of my limited experience with east coast oaks and galls. However, a friend and I are trying to raise some of these larvae to adulthood, and that will help with the ID. Adult cynipids may not emerge until spring.

Meanwhile, I was wrong about these wasp larvae having no parasites here in California. I've had one parasitoid wasp emerge so far from the galls I brought home -- posted here.

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