Praying Mantis' in Mason Bee Nesting Box?

Asked September 23, 2019, 6:34 PM EDT

While harvesting Mason Bee cocoons today (09/23/2019) from my Mason Bee nesting box, I noticed small grass-like protrusions sticking out of some of the slots (photo attached). After pulling out the grooved mason bee cocoon boards, it looks like there are many small (juvenile?) mantises (photo attached) in those slots, and maybe some eggs in 1-2 slots. I did not want to disturb them if they are mantises. After harvesting the mason bee cocoons, I returned the nesting box to its outdoor location adjacent to my vegetable garden. Normally, I would have cleaned and sanitized the nesting box and stored it until time to place the cocoons outside next year. Three questions: Are they mantises? And if so, what is a good way to ensure their survival besides leaving them alone? Or are they something else entirely?. (Sorry the pictures aren't better. Only have my iPhone camera.)

Yamhill County Oregon beneficial insects wasps grass-carrying wasp

1 Response

The grassy tufts indicate that the native grass-carrying wasp, Isodontia elegans, filled those nesting tubes. The eggs you see are most likely from these beneficial wasps. In nature, the females use hollow plant stems to build their own nests. This time, the female used the handy convenience of your mason bee nests.

The green insects in the nesting tubes are not mantids. They are paralyzed tree crickets which are "fresh" food for the larvae (youngsters) of the wasps.

See "The grass-carrying wasp" for images and additional information -
https://www.canr.msu.edu/news/the_grass_carrying_wasp_a_solitary_wasp_that_builds_nests_in_unusual_p...