Praying Mantid Ootheca, a.k.a. Praying Mantis Egg Case

A few weeks ago I noticed some kind of egg case on a bush outside of the flower shop. I wasn’t sure what it was but I had a hunch that is was from a praying mantis. Sure enough, a quick search confirmed that’s what it is.

Since then I’ve found two more egg cases in a bush in front of the house. I’ve also learned a little about this strange but interesting insect.

By VinCroce (Own work) [CC-BY-3.0 (], via Wikimedia Commons

Chinese Mantid By VinCroce (Own work) [CC-BY-3.0 (, via Wikimedia Commons

The first thing I learned is that they’re not praying mantises at all – they’re praying mantids of the family Mantidae. Within the group of mantids are three different species which we can find here in PA: the European mantid (Mantis religiosa) (from which we got the “mantis” name), the Carolina mantid (Stagmomantis carolina) and the Chinese mantid (Tenodera sinensis).

The are about 20 native mantids in North America. The Carolina mantid is the only one found in PA. This insect is about 2″ long when mature and is a brown color. The European and Chinese mantids were both introduce into the US in the late 1800’s to serve as biological control of other insects. The European mantid is about 3″ long and pale green. The Chinese mantid is 3-5″ long and usually brown and green.

I realize that most if not all of the mantids that I’ve ever seenare Chinese mantids. In the fall I often see these large insects by the side of the house. This is the time that they’re the most visible because they’re large and are focused on feeding and finding mates.

Mantid Ootheca

Mantid Ootheca

In the fall, after mating, the female mantid lays 100-400 eggs that are in a frothy liquid that quickly hardens into an egg case. This case is called an ootheca and provides protection to the eggs over the winter. It’s the mantid’s ootheca that I found on the bush and set me on this journey.

In the spring after a certain number of warm days, the nymphs emerge from the ootheca and begin to eat. Mantids are indiscriminate carnivores and this can lead to cannibalism – often their first meal is one of their siblings. They continue to fed on insects throughout their life cycle. As nymphs, they might eat aphids and flies but as they continue to metamorphosize and grow, they move on to larger prey like grasshoppers, butterflies and spiders. The traditional “praying” pose of a mantid is actually its hunting pose. The front legs are used to capture prey.

I had heard that mantids were protected but that’s simply an urban myth. The truth is that you can purchase mantid oothecae online for a few dollars each from a number of suppliers. They can be used in the garden to increase the mantid population or be hatched inside as a science project for schools.

I want to keep an eye on the oothecae that I found and hope that I’m there when they hatch. That could make for some very cool pictures. But if not, I’ll just keep my eyes open to look for mantids throughout the growing season.


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