Monday, August 29, 2011

King of the wasps

I was once again fortunate to be able to attend another excellent Advanced Naturalist Workshop at the Edge of Appalachia preserve in Adams County. My sincere thanks to Chris Bedel and Mark Zloba of the Cincinnati Museum of Natural History for letting me audit the Saturday portion. I don't know how these guys do it, but they consistently bring in the top experts in the country to teach about various facets of natural history. Be sure to attend one of these workshops next year.

Last weekend's subject was the wide and often wacky world of wasps, and the instructor was none other than Eric Eaton.

These workshops combine lots of field work with classroom lectures, just as any course on natural history should. That's Eric, 2nd from left and facing away from the camera with the hat on. Brian, far right with net, would win Olympic gold if there were a contest for bagging fast-moving insects.

Eric Eaton is the principal author of the acclaimed Kaufman Field Guide to Insects of North America. If you don't have this handy guide, be sure and get one. It is easily the best and most useful of any of the general insect guides, and Eric deserves major props for an uncanny ability to distill down the 10's of thousands of insect species in North America to include the ones that you are most likely to see. If you are a casual bug enthusiast, the chances are good that you'll find your mystery bug, to the species, in this book. If you are a bit harder core and interested in more obscure bugs, the book will quickly get you to the right family and probably genus, and you can proceed from there.

We spent quite a bit of time out in the field, and saw a surprising number of wasps. I love getting out with people who are real experts in groups that I don't know much about. It always amazes me how I'll then see a plethora of "new" organisms, even in places that I've been scores of times. Ohio abounds with wasps, and while one is likely to notice the larger flashier models there are a tremendous number of much more obscure species that require a trained eye to key in on.

I did my best to make photos of some of the wasps that we encountered, but they are often not the easiest subjects to work with. The bruiser above is a cicada-killer, Sphecius speciosa. These brutes are massive, and the females provision their ground burrows with huge annual cicadas. An egg is laid upon the unfortunate cicada, the wasps seals the tomb, and when the wasp grub hatches it is ensured of fresh meat. This rather morbid life cycle is a recurrent theme in the wasp world. Cicada-killers tend to make communes of burrows in favored spots, often dry sandy banks, and perhaps you've seen cicada-killer colonies.

The aforementioned Brian managed to net a cicada-killer and we temporarily detained her for inspection. His thumb gives you a scale of just how huge this wasp is. As would be expected, cicada-killers strike fear into the hearts of many who see them, and the first thought many people will have is that they are in mortal peril if this thing stings them. Not to worry - cicada-killers, like nearly all wasps, are amazingly passive towards people, and you'd essentially have to grab one to get it to sting you. And it'll only be females who could do that - no male wasps, of any of our species, have stingers.

Eric had another interesting point about the seemingly most ferocious wasps that possess powerful neurotoxins that can rapidly knock out large prey. If you DO get stung by one, it is excruciatingly painful, BUT the agony only lasts for about three minutes, and the sting leaves no lasting blisters, localized flesh necropsy, or other ill effects. I'll take his word on that.

Wasps most certainly do have a bad rep with the average Joe or Jane, and the group's negative connotation is largely due to a few species that are commonly encountered. The one above is probably one of them. It is the northern paper wasp, Polistes fuscatus, and they commonly build their hemispherical nests under eaves of buildings. Thus, people are occasionally stung by the protective insects.

Like many wasp species, this one spends much time nectaring at flowers; indeed, wasps as a group are major pollinators and thus extremely important ecologically. Paper wasps also capture caterpillars, which the adults masticate  - chew into a fine gruel - and feed to their larvae. I've said this before and will repeat it again: DON'T come back as a caterpillar. You'll have no friends, only fierce enemies.

Before this workshop, I didn't know much about wasps, so it's no surprise that this one was a "lifer" for me. It is a grass-carrier wasp in the genus Isodontia. These interesting animals line their nest cavities with blades of grass. They're known to use the tracks of sliding windows so you may have encountered a grass-carrier's nest and not known what it was. We even saw an adult or two flying with proportionately enormous grass blades projecting like streamers.

Grass-carrier wasps capture various tree crickets and provision their nests with them.

A beautiful but luckless catalpa sphinx moth larva, Ceratomia catalpae, is a walking dead caterpillar. This one was still alive and moving, but it won't be for long. A braconid wasp of some sort - there are scores of species - had discovered the caterpillar and injected her eggs into its tissue. The wasp grubs consumed the caterpillar's innards, taking care to conserve the most vital organs for last so that the caterpillar remains alive and better able to avoid other predators such as birds. In a grisly finale, the wasp grubs burst from the skin and create those small cyclindrical cocoons from which the adult wasps will soon emerge.

Perhaps my favorite wasp of the day - and another lifer - was this "katydid" wasp, Sphex nudus. In spite of the "katydid" moniker, as I understand it the females primarily go after Carolina leaf-rolling crickets, Camptonotus carolinensis, whch is what this wasp has captured. Just behind the wasp and nearly under that little stick is her burrow, and it was into that crypt that she dragged this victim. Same story as the other nest-provisioning wasps: find victim, paralyze victim with debilitating neurotoxin, lug victim to nest, seal victim within to eventually be consumed by the wasp's larva.

We found this cricket-killer and a number of others in the gloomy confines of a barn. The soft powdery soil in such sites is perfect for burrowers such as the "cricket-killer".

Impossibly iridescent and a feast for the eyes are cuckoo wasps in the genus Chrysis. When the light hits one just so, the wasp explodes in a riot of color. Getting a photo can be devilishly hard as they scurry about madly. They are also tough to pin a specific name on, as there are a bunch of different species and many look nearly alike.

This one and others were working the exterior of the barn in which we just observed the cricket-killer wasp. Cuckoo wasps - which have no sting - are parasites of carpenter bees and wasp species that create nests in wood. When a nest site is located, the cuckoo wasp boldly enters and attempts to lay its egg within the nest chamber. If successful, the cuckoo wasp egg will hatch prior to the host egg, and the cuckoo wasp grub then consumes whatever prey the host had provisioned he nest with, and possibly even the larva of the host species.

Note the heavy platelike armoring of this cuckoo wasp. It needs it. The wasp probably has no way of knowing whether Mrs. Carpenter Bee or other savage stinging host is in the cavity when it enters, or even more psychotically, the cuckoo wasp may know but not care. If the rightful owner is home, the cuckoo is apt to be attacked and stung, but in theory its armoring will protect it.

This is good ole Eremnophila aureonotata, the species of caterpillar-hunting wasp that I recently photo-documented in THIS POST. We saw quite a few, but none topped this cute little couple. Brian saw them in the act of producing more of themselves, and rather rudely I might add, netted the pair. When placed in a vial, they promptly went right back at it. So we gently tipped them back out of the container and onto a leaf, and they just kept going so we had some outstanding photo ops. Note the massive mandibles of the female. She uses them to grasp and carry her caterpillar prey.

Saturday evening, Eric gave a fascinating presentation entitled "Wasp, or not?". He had great images of wasps and wasp wannabes side by side, and in some cases it was quite hard to tell who the real wasp was. As we've seen, most wasps are not to be trifled with, and many other predatory animals wil have learned to give them a wide berth. Thus, if you are some lesser, harmless insect it'll benefit you to look as much like a stinging wasp as possible. Then maybe the bad guys will avoid you, too.

Well, it was our good fortune to encounter the fascinating insect above yesterday. I suppose most people would quickly identify it as a wasp and with good reason. But it isn't - not even close.

It is a moth, and I think it's Synanthedon sigmoidea but I'm not positive of the specific identity. I find it amazing that a moth, of all things, could evolve such a fantastic mimicry. And I'm sure its ruse is effective at keeping away unwanted attention.

Thanks to Eric Eaton for coming all the way to Ohio from Colorado Springs, and conducting such an outstanding workshop, and to the crew at the Edge of Appalachia preserve for facilitating these excellent workshops.

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4 comments:

Heather said...

Fascinating stuff, Jim. I hope to get in on some of these workshops next year, for sure. I'm sorry we missed the cuckoo moths during our little trek - they are really quite stunning!

Michelle from Ohio said...

I have Cicada Killer wasps that burrow in my front yard. They find an almost bare patch of "grass" and away they go. FREAKED me out the first year I noticed them...they are so huge!

A.L. Gibson said...

Awesome post, Jim! I know next to nothing about wasps but definitely recognized several from your pictures. Always nice to put a name with a face.

I had the luck of seeing a female cicada killer drag a stunned cicada into her burrow along the boardwalk at Prairie Rd Fen yesterday. There's no mistaking those flying fortresses!

Jim McCormac said...

Thanks for the comments, all. These workshops would be right up your alley, H of the H. Michelle, lucky you! Great photo ops of one of our coolest wasps, right in the yard.

You'll have to start studying wasps more closely, Andrew - after all, they are vital pollinators of many of those plants that you photo-document so beautifully!