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.
Thanks to my friends Meg Wilson and James Erdmann who identified this lady for me!