These wasps, species Pelecinus polyturator are almost always female, and when you see one with this elongated abdomen, you can be sure it’s female. Since males are so rare, they mainly reproduce by parthogenesis, which is a process by which the female actually clones herself by hatching unfertilized eggs.
A little reading about these interesting wasps has taught me that they are part of a genus that only contains three species living today, and only one species lives in North America. The very last section of the wasp’s abdomen is an ovipositor, and it uses this section to burrow into the soil searching for June bugs and other beetle larvae. When she finds a host, she lays her egg on it, and when it hatches, it uses the beetle larva for food, killing it.