Friday, October 17, 2014

Pelecinid Wasp

Pelecinus polyturator female
Sometimes a picture grabs me.  This one was sent to me by a friend of a friend and was taken when the creature had landed on the rim of his truck bed.  (My truck wasn't that clean when I bought it!)  She looks like one mean wasp, a creature that could get its stinger into your gall bladder!

Fortunately for us, she doesn't have a stinger, just an extended method of "laying" an egg.  This is a female pelecinid wasp.  They have elongated articulated abdominal segments (metasoma) with an ovipositor on the end.   You will notice that the "ankle" is thicker than the leg segment above or below it.  Also the antennae are very long, all typical of a female Pelecinus polyturator.

June beetle grub - REK
The extended abdominal segments are not just for show.  The female P. polyturator has to deposit her egg on a June beetle grub.  Her larva is parasitic and will feed on the grub as it develops.  The grubs burrow as deep as eight inches into the ground, so the female needs the long extension to reach them. 

P. polyturator male - Larry de March
Only the females are commonly seen.  The males are half their size, with the same long antennae and leg anatomy but with a shorter non-articulated abdomen.  Females don't need the males on a daily basis as they are parthenogenic, meaning they do not need to mate to produce fertile eggs.

The wicked looking abdomen probably serves to protect the wasp from curious humans but even if she used it in defense it wouldn't penetrate your skin.  It is more like a "Baby on Board" decal, so don't swat, just take pictures.

The June beetle grub is fascinating on its own, moving on its back by the use of hairs, its relatively useless legs flailing in the air.  See this previous blog.

Thanks to Brian Hoover for the picture that started this topic and to Larry de March for the use of his photograph of the rarely seen male. 

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