Oak Gall - Dryocosmus quercuspalustris

Moved

… Adam Kranz, 24 January, 2023 - 12:42am

Moved

Moved from Gall-like Structures Not Covered By BugGuide.

… Charley Eiseman, 2 April, 2009 - 3:57pm

"Roly-poly" gall

This appears to be one of the "roly-poly" galls, which are characterized by having a larval cell that rolls free on the inside. I think you would be able to hear it rattle in a mature gall, but with a green one you might have to cut it open to confirm that the larval cell is loosely attached inside.

There are three that look like good candidates in Felt (1940), p. 159. Dryphanta aquaticae is described as a "globose, hollow, plum-colored leaf gall... developing equally upon both leaf surfaces... on water oak." D. laurifoliae is simply described as "similar... length 1/5 inch" on willow and laurel-leaved oaks. D. quercifoliae is "similar... but much smaller... on turkey oak." D. aquaticae is itself described as similar to another species that measures 1/4 - 1/2 inch, but does not project fom both sides of the leaf. None of the oak species suggested below is even listed in Felt's summary of oak species, but yours is clearly a member of the white oak group, as are (I believe) all the ones I just mentioned. My sense is that the wasps can't necessarily tell these closely related oaks apart any better than we can, so I think it's within the realm of possibility that this is D. aquaticae--I'm guessing, based on nothing in particular, that your gall is in that size range. You might think it's safe to move this to genus level, but Dryphanta has evidently been dissolved, and these three species are now each in a different genus. So I'll move this to Cynipidae for now, and see if a real expert shows up to offer an opinion.

(P.S. "water oak" is Quercus nigra, which means nothing to me. I live in Massachusetts, where there are only five or so species of oak one normally comes across. I'm completely baffled by all the southern species.)

… Charley Eiseman, 2 April, 2009 - 3:57pm

Confusing oaks!

Yes, the southern oaks can be very confusing. Adding to the confusion for this discussion is that water oak (Q. nigra), willow oak (Q. phellos), and laurel-leaved oak (Q. laurifolia) are all in the red oak group, normally recognized by their sharp-tipped lobes with terminal bristles. But the latter two lack lobes at all! (Actually they have a single lobe: the tip of the elliptical leaf.) Their leaves are bristle-tipped, but many photos of them show young leaves lacking obvious bristles. Yikes!

… John Pearson, 2 April, 2009 - 4:41pm

Red or white group?

So, is Quercus austrina in the red oak group? If so, I think this must be a gall of Dryocosmus quercuspalustris, like this one:

This species is evidently not so host-specific, but is found in a variety of red oaks.

… Charley Eiseman, 24 June, 2009 - 10:11pm

Update

There's a nice list here that says which oaks are in the red oak group and which are in the white oak group. Quercus austrina is in fact in the white oak group, whereas all of the known galls with a free-rolling cell inside are on red oaks. So this is either a new host record for a known species, or (I think more likely) an undescribed species. Weld (1) is more recent than Felt (2) and only lists six galls of this type in the eastern US. Southeastern galls are poorly known and I don't think much work has been done on them in the past 50 years.

… Charley Eiseman, 6 December, 2009 - 12:16am

Southern Oaks

It was you and Charley's comments about southern oaks that prompted my trip to the local Alabama Extension Office. They didn't even blink identifying tree and gall. Now, I know my way, I will visit them more in the future.

… Robert Lord Zimlich, 4 April, 2009 - 3:24pm

"Egg"

Glad we've got a firm ID on the oak. I believe the "egg" you found inside is actually the free-rolling larval cell, which means this is in fact one of the "roly-poly" galls. Or is it stuck to the wall of the gall? If so I still think that's what it is, since the free-rolling cell must be attached initially. An egg would be very tiny, and would have hatched before the gall became noticeable. Good luck raising it!

… Charley Eiseman, 4 April, 2009 - 5:00pm

Double-checking

I wanted to be sure that those three species were indeed in the red oak group, so searched and found these on-line sources for confirmation:

USDA Forest Service, Forest Products Laboratory
http://www2.fpl.fs.fed.us/TechSheets/HardwoodNA/pdf_files/quercuseng.pdf

University of Florida Extension
http://edis.ifas.ufl.edu/TOPIC_Red_Oaks

The Wood Database
http://www.wood-database.com/wood-articles/distinguishing-red-oak-from-white-oak/

Yep, they are!

… John Pearson, 2 April, 2009 - 7:05pm

Red oak group

Well that figures! Okay, if those are in the red oak group, I definitely wouldn't want to assume this is D. aquaticae. There are some cynipids that make galls in both white and red oaks, but they're definitely in the minority. I'm confident it's some kind of cynipid wasp, but that's as far as I can go. Worth collecting and seeing what emerges, if you feel motivated to... that's probably the only way to be sure for most of the more plain, generic-looking oak galls, since there are so darn many of them. An expert would then have to examine the specimen itself--looks like virtually all of the cynipids on BugGuide that have been identified past family were ID'd based on the gall rather than the wasp.

… Charley Eiseman, 2 April, 2009 - 5:21pm

Moved

Moved from Frass. How about here? (for Charley)

… John R. Maxwell, 1 April, 2009 - 3:15pm

Good idea

Robert, I would not yet conclude that your blister is not an insect gall. Your description says that the blister extends on both sides of the leaf, but the description of the fungus deformity says that "raised...blisters may appear on upper leaf surfaces" while "the underside of the blisters (viewed from the underside of the leaf) appear as a[n]...indentation." Also, the blister in your photo is very bubble-like with a distinct border while the blister pictured in the fungus article is only subtly raised with an indistinct border.

I am glad John rescued this from Frass so that Charley Eiseman can have an opportunity to review it. It will be interesting to get his perspective.

… John Pearson, 1 April, 2009 - 3:46pm

Frassed

Now that I know what it isn't, I am relocating on FungusGuide.net :)

… Robert Lord Zimlich, 1 April, 2009 - 12:54pm

Mystery Solved

This is not a "blister-like" gall but a blister caused by the fungus Taphrina caerulescens

… Robert Lord Zimlich, 1 April, 2009 - 10:56am

Durand Oak?

Although I have a background in forestry, I am out of my home range in attempting to identify this tree, but it does look like an oak to me, too- something in the "white oak group" with rounded lobes. I was intrigued into searching, but I had difficulty finding a match. I eventually found a candidate in Durand Oak (Quercus durandii) - which I confess I had never heard of before! According to the "Eastern Trees" Peterson Field Guide by George Petrides (1988), Durand Oak is a rare oak species scattered discontinuously across the southern states, including Alabama; he emphasizes that leaves of this species are highly variable, "sometimes resembling the lobed leaves of White Oak, sometimes being merely wavy-edged." It was also hard to find additional information on the Internet, but I did find these two websites:

Durand Oak profile from Alabama Forestry Commission
http://www.forestry.alabama.gov/PDFs/100/durand_oak.pdf

U.S. Forest Service range map
http://www.nrs.fs.fed.us/atlas/tree/curr_ivlittle_808.html

Oaks are notorious for hybridizing among species, so maybe this a just a odd hybrid... or maybe Durand Oak originated as a hybrid that has been elevated to species level according to this taxonomic treatment(?).

Best I can do from a photo, I hope this helps!

… John Pearson, 1 April, 2009 - 9:34am

Other possibilities

I forwarded this posting to a colleague who studies oaks, Nick Stoynoff. He suggested three additional possibilities for identification of your oak:

Q. austrina (which is part of what was known as Q. durandii)
Q. sinuata (which is another part of what was known as Q. durandii)
Q. similis

Note that Q. durandii has been divided into two species by this taxonomy. To distinguish among these species, you need to inspect the acorns and underside of the leaves. Nick recommended the following reference:

Trees of the SE United States, Duncan & Duncan, 1988. Univ. of Georgia Press.

… John Pearson, 2 April, 2009 - 8:12am

Bastard White Oak

I had tentatively identified as Q. austrina from the choices in Trees of the Southeaster United States (Duncan & Duncan). After your comments, yesterday, I reviewed again. Apparently Q. durandii was split into Bastard Oak and Bastard White Oak.

Additionally, all my trees range between 1/2" - 3" dia.

… Robert Lord Zimlich, 2 April, 2009 - 8:49am

Tunnel Vision

John, I should have read your most recent comments before my post. Duh

… Robert Lord Zimlich, 2 April, 2009 - 8:57am

Outstanding Work

Thank you, John.

"Highly variable" is an understatement that has been a problem with identifying this tree. Almost every leaf on a branch could easily be a different tree. I finally bought a book on Southeastern Trees, yesterday. I will follow up on your work, tonight.
Thanks again,
Robert

… Robert Lord Zimlich, 1 April, 2009 - 9:48am

Oak Gall - Dryocosmus quercuspalustris

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