As I was exploring Occoquan Regional Park last week with fellow dragonfly enthusiast Walter Sanford, he pointed out a foamy-looking mass attached to the branches of a bush and asked me if I knew what it was. My first thought was that it was some sort of cocoon, but I had never seen one that looked like this. Walter informed me that it was an ootheca and when I continued to look at him with a blank stare, he explained that an ootheca is an egg case for a praying mantis, in this case most likely a Chinese mantis (Tenodera sinensis sinensis).
I did a little research on-line and learned more about oothecae in an article on the Thoughtco.com website.
“Soon after mating, a female praying mantis deposits a mass of eggs on a twig or other suitable structure. She may lay just a few dozen eggs or as many as 400 at one time. Using special accessory glands on her abdomen, the mother mantis then covers her eggs with a frothy substance, which hardens quickly to a consistency similar to polystyrene. This egg case is called an ootheca.”
Several articles warned readers against collecting one of these egg masses. Apparently indoor heat may cause the tiny mantises inside to think it is spring and you may suddenly find yourself with 400 new additions to your household.
© Michael Q. Powell. All rights reserved.
Mike Powell 
Thanks, I knew none of this
Nature is amazing.
Very interesting Mike! Now I know what to look for out in our gardens. We had a lot of praying mantises this year!
Very interesting. The appearance of the ootheca varies by species, too. I’ve never seen this sort, but I’m wondering now if a mass of bubbles I found might have belonged to a mantis.
Pretty photos. Native mantises are very hard to find. Yes, best to keep them out of doors!
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Came across info about ootheca the other day. Your post prompted me to search and I inadvertantly found a page about praying mantis and ootheca in NZ. We have a native handsome mantis that does a very neat ootheca, and a S.African arrival (1978) that isn’t so impressive. If you happen to be curious the page is: https://traviswetland.org.nz/about-travis/scientific-papers/praying-mantis-in-new-zealand/
Hi LIz, I hope you’re still finding a few natives in Clutha; I haven’t seen one here in Auckland for a couple of years, but only a fair number of the South Africans. Every time I see one I look closely, hoping for the blue spots on their elbows!
It was only on finding the article that I realised there’s two species present in NZ. Next time I spot one I’ll take a closer interest. From what I read it sounds like the S.African mantis haven’t reached this far south.
Fascinating! And the photographs are beautiful with the subject isolated against a soft background and a very limited soft palette. Gorgeous.
I had no idea. How fascinating. Thank you for sharing your knowledge as well as your images.
That is wonderful news! I love the praying mantis(es?) that we occasionally see in our yard. I will be on the lookout for the ootheca and hope I did not prune it away when I cleaned up the garden.
I love your blog!
I know the look of the egg case, but I never knew the scientific name. Thanks, Mike, I learned something new today!