Spring Challenge: find oak bud and flower galls

Oak trees host a lot of gall-forming wasps (tribe Cynipini), many of which are documented fairly well on iNat. But two of the big categories that are massively underrepresented are bud and flower galls. They’re much smaller, more ephemeral, and easier to miss, but I think often quite abundant when they occur, so if you go looking for them I think you’ll find a lot. Many if not most of these would be the coveted “first for iNat” species, and for many of them, color photos don’t even exist.

@jeffdc has already found a bunch in VA (eg this one on white oak) so there are probably a lot to be found in the southern half of the country. As spring hits your area, pay attention to your local oaks and see how many you can find!

@calconey wrote a good general note on where and how to look for galls which applies well here. For any gall observation, it’s important to also document the host plant in enough detail that its ID can be confirmed, if you’re not sure of it yourself. For spring oaks, get a picture of any old leaves from last year or spring leaves from this year if possible, of the buds themselves, the whole plant, and of the caps of acorns if present.

Spring galls are probably easier and faster to rear adults from than galls in other seasons, so if that’s something you’re interested in trying, this would be a good opportunity. Collect any galls you find and put them in a container (glass jar with peat/sand mix or just a fine mesh bag seem to be best). It would be great to have new, good pictures of these galls with IDs confirmed by adult anatomy.

Happy gall hunting!

20 Likes

Is there a particular project or tag that we should use for galls as we come across them (in nature ourselves, or while identifying on iNat)? Do you want us to just tag you in a comment directly?

I normally skip galls when identifying since they belong to a such a wide taxonomic group, but I’d like to help them get ID’d somehow.

Adding them to a project, whether local or larger can help. https://www.inaturalist.org/projects/search?utf8=✓&q=galls&utf8=✓&commit=Search
Not all project runners are super-responsive, but many are.

1 Like

Anything on an oak can safely be identified as Cynipini–there are a couple exceptions but we’ll catch them there. You can also just add them to the Galls of North America project (if they’re in NA of course).

1 Like

What is the off-white fuzzy gall under the leaves of Quercus virginiana? The tree and I are both in California, actually, but tons and tons of galls. They end up falling off eventually and so there’s all this fuzz on the ground under the tree at certain times of year.

I see on iNat a species Callirhytis furva with a lot of observations on the eastern half of the USA and none on the western. Am I likely to have that species on my eastern tree species even though it is growing on the west coast?

Any tips for flower galls? I didn’t know oaks even had flower galls. Are they evident from the deciduous catkins or do you need to search the twigs way up there?

2 Likes

Those are Andricus quercuslanigera. Both the tree and the wasp are nonnative in CA. C furva is not known to occur there afaik.

I’d be very surprised if you couldn’t find them in deciduous catkins but I can’t say I’ve seen an observation confirming that. I didn’t look for them personally last year; I’m going into this without too much more knowledge than anyone else. They should be relatively obvious if you’re looking closely, just easy to miss if you’re not. Here’s a couple examples from the slightly better-observed California fauna.

1 Like

A great idea to look for these as things start to warm up!

1 Like

I’ve been inspecting all the oak catkins I see now, but no luck so far.

1 Like

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.

@Megachile for a biodiversity survey I’m doing in Australia, I’ve found loads of galls, probably 25-30 species at least on all kinds of different hosts. But there seem to be very few resources for IDing Australian galls, so I’m considering raising some. Do I literally just snip off the branchlet, plonk it into a jar, and wait for them to emerge?

You’ll take a different approach to collecting adults depending on the inducing taxon. First step would be to dissect the gall to see what kind of thing you find inside. For hemiptera, you can just collect them out of the gall; if they’re all immature, just return later to collect adults. For wasps, you need to wait until the gall is relatively mature (not sure if there are even any gall wasps in Australia?) and place the gall in a container until the wasp emerges. Midges will often need to pupate in soil to emerge as adults.

Thanks :)

yeah there are quite a few; I’ve managed to ID some to species because their galls are quite distinct (plus host info), but others I’m struggling.

Is there a way to tell mature vs. non-mature gall?

For example, what would be your thoughts on something like this: https://www.inaturalist.org/observations/90750936

Sorry, when I said gall wasps I had cynipids in mind in particular. I bet there are non-cynipid wasp galls though probably most species of gall inducing insects are flies (as they are around the world, on non-oaks). Do you know of cynipids in Australia?

there are Australian cynipids, but very very few (I think <10 species)

Interesting topic. I’m in an area with mostly Quercus turbinella and grisea. Any advice on what to look for this spring? Also, what’s the general timing? Thanks!

There are a lot of either undescribed or highly under-observed galls on both of those oaks. It would be a tremendous help for us to have good photos of any galls you find on either. It’s very common for us to be unable to ID galls on those hosts because the images are too ambiguous or the galls are too similar. What would be especially valuable would be 1) flower galls (you’ll have to check and get a sense for when this starts in your area but early April would be a good time to start checking) 2) time series observations of the same gall as it develops 3) cross sections that show the internal structure of a gall and of course 4) reared adults we can use to confirm IDs. But really anything you get is worthwhile. Check out the list of known spring galls on Quercus turbinella. Q grisea is pretty much unknown territory at that level of resolution.

1 Like