Monday, September 22, 2014

Some random cool Hymenoptera (bees & wasps)

I have covered a lot of ground in recent days, from Cleveland to the Ohio River. Lots of cool stuff has come under the camera's lens, but I've had precious little time to slap any of it up here. So, to partially remedy that situation, here is a hodge-podge of Hymenoptera seen recently. Some of the insects in this Order rank high among our most reviled six-legged creatures, but I like nearly all of them. In spite of some of the stings that I've taken in the line of duty.

A paper wasp in the genus Polistes takes nectar and/or pollen from Gray Goldenrod, Solidago nemoralis. Goldenrods are unbeatable insect attractors in fall. This wasp is one of a number of species that makes small hemispherical paper nests that hang from a stalk. They often build in places where people will wander near, and stings are not uncommon. They hurt, too. We can just ask the artist Sigrid Nielson, who accompanied me on a recent foray. A paper wasp whacked her on the shoulder, and she reports distinctly unpleasant aftershocks.

I had been after this one for a while. It is a pelecinid (pel-ih-see-nid) wasp, Pelecinus polyturator, and they can be hard to approach. Every other one that I had encountered was during the day, and none of them ever allowed an opportunity for a good shot. We found these at night, after plunking ourselves to the ground to set up a shoot of a caterpillar. The flashlight beams drew in two of the pelecinids, and it was fairly simple to set them up for some shots.

Note the long abdomen - this is a female, and she uses that elongate body part to insert eggs into the ground and into beetle larvae. The wasp grub will then consume the host grub.

This, I believe, is a species of braconid wasp, possibly in the genus Atanycolus.Whatever it is, she's got a massive ovipositor. If it is an Atanycolus wasp, she uses that long spikelike ovipositor to auger deep into wood and lay eggs in woodboring beetle larvae.

While the previous wasp was tiny and would be measured in millimeters, this animal is huge and might send people running and screaming. It's a European Hornet, Vespa crabro, happily snacking on the head of a Common Green Darner dragonfly. The rest of the meal lies to the wasp's right, and a Harvestman is also scavenging a meal.

European Hornets are predatory and take lesser insects, but I can't imagine it took out this big dragonfly. I suspect it is opportunistically feeding on the carcass. To me, it looks like one of these would pack a punch - one can be over an inch long - but they apparently are not normally aggressive. I've seen very few of these, but they supposedly are steadily expanding their range (European Hornets were introduced in New York about 150 years ago). This weekend past, I saw two, in widely scattered locales.

Bizarre just doesn't cut it as a descriptor for this thing. One might be forgiven for thinking the waxy undulating mass to be some sort of strange fungus with the ability to glide across leaves. It is the Butternut Woollyworm, Eriocampa juglandis, which is a type of sawfly (the Order Hymenoptera includes ants, bees, wasps, and sawflies).

I was unfamiliar with this species until earlier this year, when John Howard pointed some out. Larval sawflies, at least those that do not sprout waxy filamentous growths, resemble caterpillars and feed on plants in much the same manner. This one was among many that were consuming walnut foliage.

An unadorned Butternut Woollyworm lies naked and curled next to one of its mates in costume. I am unsure of the process by which these sawflies develop their fungal-looking layers, but imagine that the disguise makes them unappealing to would-be predators.

This is one of the leafcutter bees in the genus Megachile, feeding on the disk flowers of Flat-topped Aster, Doellingeria umbellata. Note the pollen granules stuck to the bee; the earmark of a good pollinator. While it is the European Honeybee that garners the lion's share of the press, that introduced species is relatively inconsequential when it comes to the pollination of our native flora. The myriad species of native bees and wasps that have co-evolved with North America's plants are far more important than the honeybee.

LOTS of species of wasps in a number of families are parasitoids. They lay their eggs on or in host insects, and the wasp grub becomes an internal parasite eating its host alive. This behavior normally kills the host before it can complete its life cycle. Caterpillars are extraordinarily common victims.

I was photographing this Tuliptree Beauty inchworm caterpillar, Epimecis hortaria, and was so fixated on making images that I did not notice its unwelcome hitchhiker. A tiny wasp perches atop the cat, and it is undoubtedly up to no good (to wax anthropomorphic). I'm not sure of the family of the wasp - Chalcidae, Braconidae? - but it almost certainly has or will deposit eggs on this caterpillar. If so, the caterpillar's fate is a foregone conclusion, and it won't be a happy ending.

Many times, including several times in the past few days, I have taken macro images of caterpillars, only to spot parasitoid wasps on them while reviewing the photos later. An incredible percentage of caterpillars suffer such fates; some experts believe that as many as 99% of at least some caterpillar species perish due to predators, and wasps are a big part of that food web.

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