Watching Praying Mantises is an annual nature walk activity in Detroit’s Eliza Howell Park in late Summer and very early Fall. When Winter comes, long after the Mantis adults have died and the leaves have fallen, the egg cases (“oothecae”) are much easier to spot. Based on the many oothecae visible this year, the Praying Mantis population in the park will be substantial in 2022.
Most of the egg cases were clearly made by Chinese Praying Mantises, the most common Mantis here. Their egg cases are usually of a similar size and shape and location.
Recently, I found an egg case that was significantly different, different enough to indicate that it has been made by a different Praying Mantis species.
The case is smaller, more flat, placed on the nearly horizontal underside of — and flush with — a small fallen branch.
All the published information that I have seen indicates that there are only two Praying Mantises in Michigan: Chinese and European. As the names indicate, both are introduced species. They were brought to North America and released for pest control purposes over a century ago. They can perhaps be considered naturalized at this point.
The most common native Praying Mantis in the eastern part of the country is called “Carolina Mantis,” It is particularly common in southeastern U.S., the range reaching not quite as far north as Michigan.
Or maybe it is in Michigan.
In each of the last two years, a local observer has found a Mantis in the same location in Dearborn, Michigan, that definitely appears to be a Carolina Mantis. (The location is near the Rouge River, less than 10 miles downstream from Eliza Howell Park.)
It is much smaller than the Chinese and European Mantises, is mottled, and the wings do not extend as far as the abdomen does.
Compared with the typical Mantis seen in Eliza Howell, the differences are clear.
So the question that I am seeking an answer to is whether the ootheca I recently found on the underside of a branch in a brush pile is an indication that the Carolina Praying Mantis is present here in the park. That would be a great find, but,…
While I am convinced that this egg case is not Chinese Mantis, I do not know European Mantis as well. The published descriptions / photos of the European egg cases do not provide a definitive match to the recent find, but also not a definitive mismatch.
This collage (below) gives an indication of the variety of Mantis oothecae currently present in the park. At this point, I am able to identify positively only the one on the bottom right (Chinese). I am hoping/attempting to get opinions from professional entomologists on the others.
There is very little more exciting than learning something new. This latest egg case find has provided me with more information as I seek an answer to the question of the number of species of Praying Mantises present in Eliza Howell Park.