This post was written by Evan Barrientos, one of our Hubbard Fellows. Evan is a talented writer and photographer and I encourage you to check out his personal blog.
I was enjoying a sunset walk in the prairie when I stumbled upon an alarming sight: several dozen large wasps covering a clump of grass. They had menacing eyes and dagger-like stingers, but I wanted photos of this new species so I could identify and learn more about them. Cautiously edging closer and closer to the wriggling mass of black and yellow, I got my photos and escaped unscathed. Thanks to these photos I was later able to identify these wasps to the Myzinum genus, and by doing so learned that there was absolutely nothing dangerous about them.
After doing some research, it turns out that these wasps weren’t forming a murderous attack squad; they were just having a big ‘ol slumber party. Male Myzinum wasps are known to sleep together in large groups such as this, although no one seems to know why. Furthermore, males don’t even have stingers, just curved spines that seem to only serve as intimidation. During they day they feed on a vegetarian diet of nectar and look for females to mate with. The females, however, are a little less gentle.
Females actually have functional stingers and they’re bigger, built for digging underground in search of scarab beetle larvae. Like the last wasps I wrote about, Myzinum larvae are parasitoids, parasites that kill their hosts. When a female Myzinium finds a scarab beetle larva, she paralyzes it with neurotoxins injected from her stinger lays a single egg on it. After hatching, the wasp larva devours its host like a sci-fi alien.
So the next time you find a swarm of scary-looking wasps, instead of grabbing the can of wasp spray, consider that they might just be harmless insects that pollinate your flowers and eat the beetles that damage your flowers and lawn.
For more information:
The Prairie Ecologist 
Very Cool photos and description. Nature is better than fiction. Hah!
Wasps are very cool indeed! I have been scared of them before, but like you, the more I have learned about them, and the more time that I have spent studying them, the less fear I feel. Thanks for the post. Suzanne
Thanks for the good information. Between your input and Chris’s regular write-ups about insects I find them all a bit less menacing and some are quite beautiful. This from a woman who would typically run sideways to get away from anything wasp like. Again, thank you!
These sleeping aggregations are kind of cute, in a way. I wonder if this semi-social (pre-social?) behavior serves any purpose… I also love the way male bees and wasps clamp stems with their mandibles to maintain their position when they sleep. It’s a funny thing to find on a chilly morning.