03 July, 2011

Praying mantis, <i>Miomantis caffra</i>
Praying mantis, Miomantis caffra
Image: GrahameNZ
Source: Flickr

Question: What is this foamy looking thing I have found in my tree?

Answer: This object is an ootheca, (or egg case), deposited by a species of praying mantid. The ootheca is a system used by a number of invertebrates, including many molluscs and a number of the insects such as cockroaches and praying mantids. The mantids lay the eggs into a foamy protein which hardens and forms a protective case, while the ootheca of cockroaches is usually covered by a thin layer and often looks like a small purse or pod.

Cockroaches and mantids differ in their use of the ootheca in that the mantids usually deposit their oothecas on vegetation or sometimes a surface like a wall or brickwork, while many species of cockroach carry the ootheca around attached to their abdomen, (others have the ootheca held inside the body).

The ootheca of the praying mantid is often characteristic of the species and can hold from 10 to 400 young. The young can take from 3-6 months to emerge. If you find a mantid ootheca some people are tempted to take them inside to try and see them hatch. This may not be the best thing for the young mantids as the warmer conditions in the house can cause the young to hatch earlier than they should and if there is insufficient food the young nymphs may eat each other. The best thing is to leave it where you find it and observe it as we move into spring and see if you can observe the young emerge. Praying mantids are great to have around the garden as they consume numerous insects and are fascinating to watch.

Comments (3)

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GrahameNZ 15 November, 2013 10:31
Interesting, This is my image and I sure as didn't post this question !!!!!!! For the record it wasn't in a tree either it was on the side of the house I was living in at the time. This is the ooth of Miomantis caffra an unwanted Mantis import into New Zealand.
Discovery Centre 16 November, 2013 10:39
Hi GrahameNZ, apologies if you thought we were implying that the article online was a question posed by you. We were using one of your images to answer a public enquiry about what an ootheca was. In searching for images we found yours which says on creative commons it could be used for non-commercial purposes. Please let us know if you don't want us to use it and we can remove the image.  
commonly known as daz 30 November, 2013 00:35
does anybody know roughly how long a miomantis caffra ootheca usually take's to hatch ? i have kept the ootheca at a good temperature.
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