Praying mantis egg sack

Asked March 11, 2019, 12:11 PM EDT

I found a praying mantis by my door October 28th, she couldn’t fly. I brought her in and put her in a 70 gallon tank with plants and crickets she ate well on thanksgiving day she layed an egg sack, she died 5 weeks later, I have been watering and occasionally misting the hemlock plant she layed the eggs on. Yesterday 3/10 I noticed what looked like web coming from the sac hanging about an inch with what looks like some babies maybe 10 or 12. It was chilly out here yesterday maybe 45 a friend said put it outside it might prevent them from hatching out, he said it would be a big job in the tank. I did put the plant in the ground in a protected spot with leaves and a cut Christmas tree as a wind buffer and to protect the Bush. After about a 1/2 hour I had a Change of heart and brought it back in. It isn’t really doing anything now a day later???? Do you think I killed them or delayed them or do you think that was all that it was going to do. Not sure what to do. Bummed out. I called around yesterday for the wingless fruit flies and they were out so I would pick them up today if they will start hatching again
the fist picture is before I brought them out . The second is today again.

Monmouth County New Jersey

1 Response


The praying mantis egg cases are normally laid outside on tree branches, and will be dormant over the winter. Eggs hatch when temperatures moderate enough in the spring. I'm afraid that maybe your efforts to protect the egg case inside led to premature hatching of the young. It was probably a combination of temperature and moisture. They would need some sort of food source, which would normally be available later in the spring. I know you meant well, but you probably should have put the egg case outside after it was formed and the female died. Hindsight doesn't matter though. If you leave the egg case out now, it does run the risk of alternating freezing and thawing. It is those fluctuating temperatures that harm both insects and plants. There will be many other out in the landscape. Enjoy them, but let them run their course in their natural environment.
Thanks you for sharing your story and your good intentions. Thank you for contacting Cooperative Extension,