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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 "
There are 2 out of 12 immature Oak trees planted around a soccer field inflicted with fuzzy galls on the underside of most every leaf . I don't know what kind of Oak tree it is , but it has small leaves in varying sizes up to 2 1/2 " in length . I only found one tiny acorn on this tree . Thanks , Beth

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

Moved from Andricus laniger.

Moved from Gall Wasps.

which soccer field?
Which soccer field were the trees planted around? I may be near Manteca next week and might have a look.

Manteca soccer field / Gall on Oak
Hi Joyce . I am not sure if the park is named . Take Louise turnoff from freeway ... go down about 3 miles over 3 railroad tracks ( just after 3rd track ) then make a left turn on Marguerite which turns into Nicol ... go straight about a half mile and on the left is the grassy park . The Oak tree with the Galls is the first one ( right after a small dead tree ) in line just after the childrens playground along the cement wall/fence . Also , on the other end of the park there is another tree with many of the same fuzzy galls on the leaves ... it is closest to the wall from the sidewalk ( across from fenced off utility ) . Hope these are good enough directions , Beth

perfect directions -- thanks
Hi Beth -- I went to the field on Monday. Very good timing because I was on my way to meet up with some cynipid gall researchers, including three from Europe who have been traveling in the U.S. to find cynipid galls. I showed them photos, leaves, acorns, and galls. We decided that the oak is Quercus virginiana which is native to the southeast. We all agreed that the galls (and their wasps) are not native to California either. Probably when the trees were brought to California they came with some eggs or wasp larvae already on them, and they developed and have been doing well ever since. They probably have no parasites here, and they probably can't live on any of our native oaks, so they will have a very limited distribution in Primavera Park as long as those trees are there. I found no galls native to CA on the trees. But like you have shown us, these trees are sure covered with the galls that they do have!

It's not that common to find non-native oaks with galls from wasps that normally only occur where the trees are native. So this is an interesting find.

As to which species of cynipid these are, no one knew off-hand. I'll spend a little time looking at what few (old, incomplete, and out-of-date) book resources there are -- haven't had time yet. So far it seems that there is more than one possibility for what species this is. More on this later. Thanks for posting these interesting photos.

still not sure...
Thanks for posting the leaf photos Beth. Unfortunately I'm still not sure of the species of oak OR wasp, but if you leave the photos here I or someone may eventually figure it out. Also, if you find a mature (big) acorn on any of the trees, even if it's not from one of the trees with the galls (but is in the same line of trees with the others -- the same species, presumably), it would be great to have a photo. Yes, the acorn you have here is a bit stubby.

This is made a little more confusing by the possibility that the oak is not native to Manteca (since they were planted)...