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Hi there,
Thanks to Cindy for sharing Jeff's photo, and to Randy,
Chris and Steve for commenting on it. I saw one of these wasps today
in my own garden, and knew immediately what it was, thanks to this
list. I noticed the swollen hind legs, but even with my binoculars
could see only four legs in all. (The Wikipedia photo shows
six.) Does this creature often hold its front two legs up close to
its body, as a butterfly does?
Steve, I took it that "attenuated" referred to the gradual
thinning of the wasp's abdomen - not its length.
Cheers,
Patricia l. Chalmers
Halifax
At 07:52 PM 13/08/2008, you wrote:
>I see a few of these wasps cruising very slowly over my "lawn"
>(actually mostly
>moss) in Halifax in late August most years.
>
>Of some related interest is the extremely overdeveloped tibia of the
>hindlegs of
>these female pelecinids, nicely visible as the seemingly swollen part both on
>Cindy's nice photo and on the one in the Wikipedia article that Randy listed,
>link copied below. Most insects have a vibration-sensitive organ in
>each tibia
>(the SGO or subgenual organ = the under-the-knee organ). The SGO in the back
>legs of cockroaches is extremely sensitive -- it can detect vibrations on the
>order of 1 nanometer (= a billionth of a meter) at frequencies around 1
>kilohertz. As the pelecinid's hind tibia is much more developed than the
>roach's, it could be specialized to detect and localize vibrations made by the
>June beetle larvae moving underground, in whatever frequency band these larvae
>emit (not measured as far as I know, and I'm not sure technically how you'd do
>it in soil). Perhaps they use their tibial SGOs to locate the appropriate
>place to insert the abdomen into the soil. Some years back I sent a couple of
>pickled legs to a German academic who had a mutual interest in pursuing this
>possibility, but as far as I know, he never got round to doing anything with
>them.
>
>Incidentally, language purists may wish to scrutinize the one-paragraph
>Wikipedia article on this for a creative re-definition of the word
>"attenuated", used in reference to the extreme length of the pelecinid's
>abdomen.
>Steve, Halifax.
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