#pelecinus

American Pelecinid Wasp - Pelecinus polyturator

I nearly blinked and missed this little insect as it darted throughout these flowering plants and then escaped into the distance. Just to be clear the leaves seen here are not only very large, but this Wasp is also on the smaller side. Based on the images here, if the identification is correct there's only one species that it this Wasp could possibly be, as all other Pelecinid Wasps within the Pelecinus genus are documented to have their habitat outside of North America. The wing venation and patterning is furthermore promising, as is the time range of late summer, but the coloration on the end of this insect's legs, and the markings on its body and face cast a bit of doubt on the certainty of identification here. However, this is an observed point of research and discussion for this particular insect; there are some who that differences in coloration suggest a complex of species, while other professionals have the opinion that this is simply individual variation. Alternatively, this could be a different Wasp altogether, as the wing-markings on its body and head are quite prominent. A find like this individual would benefit from further comparisons to other similar-looking Wasps found within the area, so hopefully more individuals can be found in the future.

Looking closely and observing the images of this individual further, it's quite clear to see that it has slightly widened hindlegs, and a bulbously-tipped abdomen which is connected to the thorax with a very thread-like petiole (wasp-waist). As such, this could very well be an American Pelecinid, and not only is it a relatively small Wasp, it's even smaller (and rarer) than the expected find for this species. Specifically, this particular individual's abdomen length indicates that it's actually a male specimen. Naturally, the female Wasp possesses more specialized equipment compared to her male counterpart and she also tends to be larger and longer! To clarify, this is a type of parasitic Wasp, but it belong in a distinct family (Pelecinidae) compared to the more well known Ichneumonid (Ichneumonidae) Wasps. As a comparison between the two families, Ichneumonid females possess elongated ovipositors (which are sometimes mistaken for stingers), while the females of Pelecinid Wasps instead have elongated, articulated, slender abdomens. With an extended length combined with the flexibility allotted by her abdomen's segments, a female Pelecinid Wasp can place her eggs upon subterranean Beetle larvae with incredible maneuverability, flexibility, and precision. Finally, despite the elongation of a female's abdomen, a male (like the individual pictured here) surprisingly has few issues when attempting to form a mating pair. Rather than directly mount overtop or to the side, the male will instead mount the female's abdomen directly so that their gasters connect, without needing to fold or twist around.

I'd also like to extend a thank you to fellow blogger Mariapoda for letting me know that the family information regarding this Wasp was initially incorrect. This just goes to show: DO NOT compulsively identify all parasitic Wasps as Ichneumonids. As such, this post's information has been revised to more accurately reflect information related to this Wasp and showcase it properly. The feedback was greatly appreciated!

Bug of the Day

Pelecinus polyturator, a kind of parasitoid wasp. They lay their eggs inside beetle grubs using their wacky “scorpion tail” and their larvae eat the grub from the inside out, killing it. Killing their host is why they’re parasitoid- normally parasites, such as tapeworms, don’t “want” to kill their host because that would kill the parasite. Not Pelecinus. Pelecinus don’t care.

Pelecinus polyturator is apparently widespread in North America; I took this picture in Cheyenne, WY (where I had to go for a doctor’s appointment, which has an interesting biological backstory that I’ll write up eventually). However, Pelecinus also occurs in South America; I saw them with some frequency in Ecuador.