Solitary wasp, interesting prey carrying adaptation, ID help

Charles Krebs · Post by **Charles Krebs** » Fri May 25, 2007 4:20 pm

I have this small wasp, (about 10-12mm length) that has some very unusual adaptations for catching and carrying prey. I've not seen it before and would greatly appreciate any guidance toward some level of ID.

This small wasp has rather ornate, thin "shields" attached to a front leg segment (the femur I think). At the base of the femur is a serious looking pincer, and at the end of the front leg is one of the most elaborate claw structures I've seen. It's a little tough to "read" the picture because of the odd way the leg is jointed and shaped.

The top shot shows the features I've described. The bottom are crops that show the pincer and claw. (I hope to put these under the microscope to get more detailed shots).

beetleman · Post by **beetleman** » Fri May 25, 2007 5:32 pm

What an incredible set of photos Charles. That creature is so strange. I can see exactly what you are describing and it looks like it has a very specific purpose. The closest thing I can come up with is some kind of dryinid wasp. The females are supposed to have front tarsi that are pincer like. Antennae 10 segmented, rising low on the face and not distinctly elbowed. Larvae are parasites of planthoppers, leafhoppers and treehoppers. Not 100% sure though

This is according to Peterson field guide to the insects. The hind wing is supposed to have a spur or what they call a jugal lobe along the lower edge near the thorax and reduced venation in the wings. Peterson shows the female with wings, all of the pictures I see on the web are wingless

rjlittlefield · Post by **rjlittlefield** » Fri May 25, 2007 8:33 pm

What a bizarre creature! I have no idea what this is, but I surely am looking forward to finding out!

I don't feel at all comfortable about Dryinidae -- words like "raptorial forelimbs" [ref] and "chelate foretarsus" [ref] sound like a good match as words, but the pictures I can find don't look even close.

Charlie, can you tell us some more about where you found this beast? Is it one of a kind or did you find others at the same place?

And (oh yeah, I forgot for a moment that this is a photo forum

) what can you share about how you shot the pictures?

Speaking of forums, have you posted this creature to BugGuide.net to see if somebody there recognizes it?

--Rik

Charles Krebs · Post by **Charles Krebs** » Fri May 25, 2007 9:25 pm

Hi Rik and Doug,
I just did these and have only posted them here. Found it by Lake Sammamish here in Issaquah (N 47.552 W 122.067). The blackberries are just starting to bloom and there are all sorts of bees and small wasps around them. This was the only insect I collected, and it was pretty small. I could just barely make out something "different" by eye, but I thought it was an attached mite or some sort of parasite. I found the interesting physiology when I put it under the low power stereo scope.

It has the "typical wasp" slender waist and black and yellow striped abdomen. It is very hard to photograph in a way that provides a good sense of the structure. In "person" under the stereo scope, is appears that the "shields" together with unusually jointed legs, pincer and claws would allow this wasp to grasp around the body of it's prey and the shields would form a nice aerodynamic cover "shell". (Note also the black and yellow coloration of the shields... much like the abdomen).

The pictures above were stacks taken with a Canon 35/2.8 Micro lens on a bellows with the Nikon D200. (The high mag double pane shot is just crops from a full frame).

I've added another shot below taken with a 50/2.8 El Nikkor reversed on the bellows. Whiffle ball lighting for all.

DaveW · Post by **DaveW** » Fri May 25, 2007 10:29 pm

Those things on the legs look rather like some form of catching bag for insects, rather like a catchers mitt in baseball, or how they now provide a web between thumb and fingers on cricket wicket keepers gloves so the ball does not slip through?

Would not have thought they were air brakes.

DaveW

rjlittlefield · Post by **rjlittlefield** » Fri May 25, 2007 10:56 pm

Fascinating critter.

I strongly encourage you to post at BugGuide.net. I just can't think of a good substitute for getting a few dozen people who care and already have their memories loaded up, to take a look at your problem.

About the images, they're beautiful stacks, of course. But I wonder, in this case, whether the high resolution stills might be supplemented with some low resolution stereo or rocking shots to better show off the unusual structure.

I think I have the structure figured out at this point, but as you suggest, it has been a bit of a struggle!

--Rik

Planapo · Post by **Planapo** » Fri May 25, 2007 11:25 pm

Charles, excellent images as always!

They show a male digger wasp. There used to be only one family, the Sphecidae, but there has been a split not too long ago, so you will find a familiy Crabronidae also. (Depending on publication date of literature)

It´s the tibia that is broadened and the "boy" has these strange "forearms" to hold his "girl" in a special grip.

This should be a male of the genus Crabro. Or a related genus of the subfamily Crabroninae.

(Note, I am not familiar with your North American fauna and haven´t got the time to check it out to make absolutely sure. But I think, now you´ve got a starting point for your ID)

Best regards.
Betty

Charles Krebs · Post by **Charles Krebs** » Sat May 26, 2007 12:58 am

Ah... Betty comes through once again!

Very interesting. Thanks!

MacroLuv · Post by **MacroLuv** » Sat May 26, 2007 2:15 am

Charles, perfect images and incredible finding!

Betty, you worth your weight in gold for this forum!

beetleman · Post by **beetleman** » Sat May 26, 2007 3:10 am

Well, it sure is a special find Charles, Beautiful and strange. I was off on my hunt for an ID. I never knew there were strange wasps like the dryinid wasps also. The segment count on the antennae did not match up either. I love the way your insects are super clean and not a hair out of place. Fantastic work Charles.

Bruce Williams · Post by **Bruce Williams** » Sat May 26, 2007 5:53 am

Wonderful colour and extraordinarily clean detail - so much to look at - and so thought provoking too!

Thanks,
Bruce

Gordon C. Snelling · Post by **Gordon C. Snelling** » Sat May 26, 2007 6:35 am

Great wasp, I know it but am drawing a total blank. Definitely not a Dryinid though. Will get my dad to take a look and get his opinion.

Ken Ramos · Post by **Ken Ramos** » Sat May 26, 2007 6:39 am

I don't know what it is but the first image is a killer. Awesome photograph!

rjlittlefield · Post by **rjlittlefield** » Sat May 26, 2007 7:46 am

Betty, many thanks for the ID!

BugGuide does have a few other pictures of these, see for example http://bugguide.net/node/view/19413/bgimage. None nearly as nice as Charlie's, of course. And it works best to search under Crabroninae -- "crabro" also picks up lots of Vespa crabro, the European Hornet.

According to the entry in BugGuide,

His front tibia are greatly expanded into those shields so easily visible here. He covers the female's eyes with those things during mating. The plates don't blind her, but apparently filter light in such a way that she recognizes this is a male of her own species. How weird is that?

--Rik

beetleman · Post by **beetleman** » Sat May 26, 2007 9:23 am

Nice find Rik.