Posts Tagged 'galls'

More Galls

gall2The world of galls is vast: I don’t know what these are, but they evidently darken into these rather glossy, bean-like structures:gall1gall3Another. It’s just a splotchy discoloration on the top of the leaf, but underneath there’s some interest.

Some Southwestern Insects

Aglais milbertiMilbert’s Tortoiseshell (Aglais milberti). I’ve only identified a couple of the following, so holler if you know any of them.
i14
i2
i6
Battus philenorPipevine Swallowtail (Battus philenor).i16i10This katydid was dropped in front of me by a surprised Western Tanager. I think the katydid was surprised too, if not in shock.i5Like the chimney-shaped ant colony entrance, this is another sign of an insect, in this case a gall-maker (evidently several species make willows produce these cone-like structures).

Cocoon

Still visible on some bare trees out there, these hanging gardens are the cocoons of a bagworm moth in the family Psychidae.
There’s a caterpillar in here who made this hanging tent of leaves last year so it could overwinter. There are some 1300-plus known members of the Psychidae world-wide. The better known in our region use conifers, but some will use deciduous trees, gathering material from the tree to make the shaggy cocoon.

I had at first thought these some new to me form of gall, but bugguide.net set me right.

Emergence

wasp“Paging Dr. Kinsey, paging Dr. Kinsey! Gall wasp emergence on Henry Street…”

Before he went into human sexuality in a big way, pride-of-Hoboken Alfred Kinsey was a specialist in gall wasps, a vast and largely unknown kingdom, at least to us non-specialists.

Back in early February, I posted about two species of gall wasps on an oak in Green-Wood. I bought a couple of the galls home to photograph. One of these had no exit holes, so I popped it into a little plastic box with a magnifying lens built into it. Yesterday, I noticed something moving in it. From the corner of my eye, I thought ant, and thought it must be outside the box. But it was this 5mm gall wasp inside, crawling about. (Ants and wasps are of course in the same order, Hymenoptera, so the morphological similarity makes sense.)

I placed the box into the freezer for about a minute to get this wasp to play dead momentarily for the camera.

Galls in Winter

White oakThe leaves of this White Oak in Green-Wood have refused to fall. They held up to Sandy, the Nor’easter a week later, and all the rest of the winter so far. Actually, some oaks are tenacious leaf-holders, only shedding them just before, or just as, new leaf growth begins to bud.hedgehog gallsSo I got to take another look at the hedgehog galls I noticed back in August. They’ve lost their lurid coloring. hedgehog gallThe exit holes: the female wasps within (there are only females this generation) should have emerged during autumn to deposit over-wintering eggs on the tree’s buds (I looked but wasn’t sure what I was looking for); the generation from these eggs on the buds, which will hatch out in the spring, will be the reproductive one, producing both males and females.hedgehog gallRemember that these galls are created by the tree itself, as a kind of containment system around the irritation of the gall wasp’s eggs and then larvae. The miniscule wasp is forcing the tree to house and protect its tender larvae, chemically commanding the tree to work for it (most galls are harmless to the host plant). The image above shows where the gall was attached, extended, connected to the leaf. And inside?hedgehog gallSliced roughly in half, the tunnel is clear but the chamber within is filled with frass- or sawdust-like material, presumably left over from the adult insect cut its way out.

Oaks being gall-magnets, the same tree had examples of another type of gall. These were on the twigs, not the leaves. Now, I don’t know which type of insect produces this gall, I’m guessing another wasp, but then I’m no Alfred Kinsey.gallSome of these also had had exit holes:unknown gallSome didn’t. I sliced one of the latter in half:gallA tiny egg-shaped structure was inside the cavity within. You can see where the plant ends and the animal begins. And inside of this eggy cocoon, the larva:larva

For more on galls, see all other posts on the subject.

Gall-ish

Plenty of oaks yet to turn color in the Hudson Highlands, 60 miles north of Brooklyn.

And where there are oaks, there are galls. Here’s one I came across up there recently:Not sure what species is inside here.

To re-cap, galls are formed by the interaction of animal and plant. Irritated by wasp, mite, aphid, midge, even nematode, etc., the plant is stimulated into forming a growth which is then used by the animal to protect its eggs, foster its larval stages, etc. Galls can be found on all parts of a plant, leaves, flowers, stems, bark, roots. The most obvious are the ones on the leaves, and oaks in particular seem to have a strong affinity, if that’s the word, for gall-making insects that create oddly wonderful oak “apples.” The plant is generally not harmed by this interrelationship, the benefits of which are partaken by well over 1000 (in North American) species of insects.

Here are some of my previous adventures amongst the galls.

Hedgehog Gall

Hedgehog gall, caused by a tiny cynipid wasp, Acraspis erinacei, on leaves of White Oak (Quercus alba) in Green-Wood Cemetery.There are three to five larval cells in each of these galls. Only female adults will emerge from these in the late fall, and lay eggs (without mating) on leaf buds. These eggs over-winter, hatching in early spring. The resulting larvae will then develop in other galls, and emerge as adults of both sexes, who mate. Mated females then lay eggs on leaves. When these eggs hatch, they stimulate (annoy?) the tree to form these furry galls, which protect the larvae.Before he got bogged down the relatively simple complexities of human sexuality, Alfred Kinsey was a cynipid wasp expert. There are thousands of gall-forcing organisms, wasps, mites, fungi. Oak species are associated with hundreds of them.

Here are some I’ve come across.


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