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Gall on oak tree ? - Andricus quercuslanigera

Gall on oak tree ? - Andricus quercuslanigera
Manteca, San joaquin County, California, USA
September 17, 2007
Size: varying sizes up to 1/2 "
At first I thought these were caterpillars . They appear to be some type of gall on the underside of an Oak tree's leaves . Has anyone seen this before and do you know what caused this ? I found a couple of curious firefly's inspecting some of them , but that was the only insect I could find . Thanks for any comments , Beth I found it weird that these fuzzballs were only on this tree and not the others .

Images of this individual: tag all
Gall on oak tree ? - Andricus quercuslanigera Gall on oak tree ? - Andricus quercuslanigera Gall on oak tree ? - Andricus quercuslanigera Gall on oak tree ? - Andricus quercuslanigera

Moved from Andricus laniger.

Moved from Gall Wasps.

more photos of leaves

Can you take some photos of the leaves of this tree? Canyon Live Oak doesn't grow where you are, it turns out. Also if there are any leaves that look different from the others, get those in a photo too -- ie, if some have wavy, lobed, or spiky margins, get photos of those. The leaves in your other photo seem to have mostly smooth margins but it's hard to tell.

Also, if there are any acorns, a photo of one would help.

Do you think these trees were planted? You mention that there was a line of 6 oak trees -- do they all have the same shape of leaves?

You can email me photos if you don't want to clutter up bugguide with leaf photos.

yes, wasp galls
Do you know which species of oak these were on? (It looks like Canyon Live Oak, Quercus chrysolepis... is it?) That would help nail down a species ID.

Meanwhile, yes, the galls are made by the larvae of wasps in the family cynipidae. I've been slowly posting CA gall photos to Bugguide and CalPhotos. I think your galls are a species I don't have online (but do have in my files...). That's quite a lot of them on one tree! It's normal for one tree to have lots of galls and the next trees have few or none.

A great new reference for California galls is Ron Russo's gall book.

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