How to Tell a Carolina Mantis Eggcase from a Chinese Mantis Eggcase (What’s an Ootheca?)
The Bunched Arrowhead Heritage Preserve is one of my favorite late-day stops when I need to get a nature fix. It’s about 20 minutes from my house and offers a range of habitats to explore — including forest, rare wetland seepage areas, and maintained meadows.
Meadow habitats have become so scarce in the Carolinas that DNR uses mowing and controlled burns to renew it every few years. By the second year, fast-growing pioneer tree species such as sweetgum have peeked their heads over the grasses. When I went a couple of weeks ago I saw dozens of praying mantis oothecas pasted to the whip-like sweetgum trunks.
What’s an ootheca? It’s a communal insect or mollusk egg case. In this instance I could recognize which species of mantis it was even from a distance.
Chinese mantids (Tenodera sinensis) have been naturalized in the USA since at least 1895. They have color morphs that range from brown (with a green wing stripe) to solid, bright green. Their oothecas are a little smaller than ping pong balls and fairly round. If the front of the ootheca looks like tiny Venetian blinds (photo from The Enchanted Tree) you will know that the approximately 200 eggs have already hatched and moved on.
These are the most common mantis egg cases that I see and the species has a wide range. They are also the mantids you can buy from natural pest control companies.
I can usually find mantis egg cases decorating our yearly Christmas tree (look all inside the branches — they are sneaky). If left indoors for the holidays the baby mantids will assume the warmth of your house means spring — and hatch. They’ll starve in the winter so I quickly move the oothecas into a shady spot in the garden. Oothecas that are in full sun can get unseasonably warm and hatch too early.
The Carolina mantis (Stagmomantis carolina) is my state insect. I love the idea of state insects, and I wonder how many people know theirs?
Gray and brown camouflaged Carolina mantids are smaller and less showy than Chinese mantids. They are around in the warm months but easier to spot when they reach adulthood (around August). Their ootheca is elongated and more slender, though you can still tell when they have hatched from the Venetian blinds look.
Sometimes caterpillar egg masses get mistaken for Carolina mantis cases. These Eastern tent caterpillar eggs are darker and harder than mantis oothecas.
Here’s what the adults look like:
And hey, while I’m at it, it is an urban legend that female mantids eat their males during copulation. That happens in laboratory settings when the female is starving… and then who can blame her? 😉