This is a strong contender, if not outright winner, for the What’s Buzzin’ photo submission of the year. Wow! Kyle went to move a flower pot in his backyard and found these larvae on the rock underneath. He quickly took a photo and gingerly put the pot back, with the hope they can still develop.
So, what exactly is going on here? We believe this is the cells / nest of a species of mason wasp. The female wasp will sting and paralyze caterpillars to then add to the mud cell she creates, where she will lay just one egg. The larvae will emerge and eat the paralyzed but live caterpillars. The large larvae toward the top have already consumed much of their stash mom provided and will likely pupate soon. The cells toward the bottom have small larvae in them with lots of food remaining (possibly just an egg in some cases) …so the cells at the top were likely created by the female wasp first — the eggs hatching a few days earlier. We would guess this is the work of a single female wasp as they are not social.
Photo by: Kyle Hartse on 7/2/21 in Helena, MT