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Callirhytis quercussimilis - Zapatella quercusphellos

Callirhytis quercussimilis - Zapatella quercusphellos
Marlton, Burlington County, New Jersey, USA
April 14, 2008
I forgot to measure, but somewhere between peanut and almond (maybe) :-) This is in my backyard, I think on one of the little oaks that live under/amongst the pines.
1) Is this a gall
2) Is it the kind made by a Ruptured Twig Gall Wasp (Callirhytis perdens)
3) How can I find out FOR SURE! Wrap it in a plastic bag and wait. Or maybe something more mesh, but I assume very small holes?

Images of this individual: tag all
Callirhytis quercussimilis - Zapatella quercusphellos Callirhytis quercussimilis - Zapatella quercusphellos Callirhytis quercussimilis - Zapatella quercusphellos Callirhytis quercussimilis - Zapatella quercusphellos

Moved from Gall Wasps.

Moved from Galls.

Any news on this one?
I imagine you would have mentioned it if something had emerged from this... but maybe you can add a photo of the leaves so we can figure out what species of oak it is, if you haven't already figured that out? I'm not recognizing the buds, but maybe that's because they're getting ready to open... terminal buds would be easier to recognize.

never got anything I could say came from the gall. My wife says that it is a "Blackjack Oak", but that doesn't mean much to me. Little short scraggley thing. I'll try to get a shot and post to confirm.

Same tree/branch as these. Could they be related? Different manifestations of the same cause depending on the tissue type attacked?

Possibly related, but not necessarily
Not only are cynipid wasps very particular about what species they use for a host, they're very particular about the type of tissue in which they're ovipositing. There are some species that have alternating generations with two types of galls--I need to read up on this more, but I believe it involves leaf galls in the summer and twig galls to overwinter. So it's certainly within the realm of possibility, but with hundreds of species of cynipids that make galls on oak, I wouldn't assume it's the case here.

Added a couple of shots to frass just to confirm species.

Black jack oak
I'm not too familiar with oaks that aren't found in New England, but looking at online images, I see no reason to doubt your wife's ID, which would be Quercus marilandica. Felt lists many similar twig-swelling galls on oaks, all of them made by cynipid wasps, but none of them on black jack oak (there's one on blue jack oak, but the leaves are totally different on that species). While it's possible that this is some other similar kind of oak, I think it's just as possible that these galls are caused by an undescribed species of wasp--or one that hasn't been linked to a gall yet. It does seem to be pretty safe to call them cynipid wasp galls though.

Further thoughts
Well, actually, Callirhytis crypta makes twig galls on black jack oak, but they make only a slight swelling if anything at all. There's an image here. But Felt has a photo of a gall that looks exactly like yours [plate 33, #7], attributed to Callirhytis similis, which is found on scrub oak, blue jack oak, shingle oak, Spanish oak, Quercus myrtifolia, and Quercus texana. So it's looking likely that this is a gall of some Callirhytis species, as you originally suggested, and C. similis seems like a likely candidate, as it evidently isn't very host-specific, but with these fairly nondescript twig-swelling galls it's hard to name a species with complete confidence.

I seem to remember there being some doubt if it was Black Jack or Scrub Oak, maybe I better check again.

for what it's worth, I would have called it scrub oak if I'd found it in Massachusetts, but I'm totally unfamiliar with black jack oak.

Scrub oak, but I may need to look for acorns to be 100% sure! Now just 99% ;-) Looks like too many lobes at the base of the leaf to be black jack which seems to be lobe-free until the last 1/2 or 1/3 of the leaf tip.

1) Yes, it looks like a gall.

2) It is likely made by a cynipid wasp, but probably not Callirhytis perdens. All the cynipids I've been aware of on the east & west coasts are different species -- as are the oaks. Cynipid wasps are EXTREMELY fussy as to what oak species they use. Can you find out what the oak species is? The species is critical to any ID of the gall. Weld (1) lists galls by oak species ... though often one wasp species can use more than one oak species as long as the oaks are all in the same group (ie, white, black, red...). There are quite a few species of wasps that cause stem galls.

3) You can wrap something around the branch and see what emerges, but keep in mind that whatever emerges may be as small as 1mm. It may be the original gall inducer, or an inquiline, or a parasitoid. Even if you get the original gall inducer that will not help much with species ID (unless you study cynipids...) :(

Another thing you can do is clip the branch off and put it in a sealed container. If the wasp(s) have already pupated, or are almost ready to pupate, they may emerge even though you've clipped off the branch.

I slid a plastic bag over the branch and tied it on. Maybe I'll get lucky.

Nylon stocking
works well. It can breath.

I slid a bag (like the newspaper comes in) down over the branch - leaves and all. It "sweated" and had a lot of condensation. I was afraid if anything came out of the gall it would drown in the corner of the bag.

Helpful hints
like these would be great additions to the "Galls" guide page, I think.

keep us posted
Also, Callirhytis perdens is not listed in Weld's Cynipid Galls of the Eastern United States (1) -- I checked.

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