Friday, April 10, 2009

Our mantises hatched! Great for the garden!

Sadie Kneidel at age 6, with an adult praying mantis full of eggs. Photo by Sally Kneidel.

We used to keep praying mantises a lot, back when I was a science teacher and the kids were little. I used the picture of Sadie above in a book I wrote for teachers in 1993: Creepy Crawlies and the Scientific Method. This particular mantis was one of our favorites, she was quite tame. She laid her egg case soon after the picture was taken and then died, as they always do after they've reproduced. Just like the spider Charlotte in Charlotte's Web. But when her egg case hatched the following spring, we raised her youngsters in one of my classes. When school was out for summer, we released them all outdoors.

Ken (my husband) is still teaching biology, and last fall he found a praying mantis egg case on a twig. He broke the twig off and put it in a "sleeve cage." He left the cage outside all winter, so the eggs would hatch at the proper time, in spring. (Indoor heat will speed their development and make them hatch unnaturally early, in mid-winter.)

Yesterday (April 10) something exciting happened - our mantis egg case in the sleeve cage hatched!

The sleeve cage on our deck. The sleeve lets you put your hand inside without taking the lid off. Photo by Sally Kneidel.

The mantis hatchlings inside. The egg case is visible on the twig in the center. The little specks on the mesh lid are the hatchlings. (Click on photo to enlarge.) Photo by Sally Kneidel

The mantis nymphs emerging from the egg case. Photo by Sally Kneidel.

Just-hatched mantises wandering around the sleeve cage. Photo by Sally Kneidel

The young mantises don't eat for the first day or two after hatching. We give them water by spraying a fine mist onto the sides of the cage; they'll drink the droplets. (Adults will readily drink from a spoon, while sitting on your hand!) Today Ken fed them for the first time. They're predators, and have to eat live insects. Ken gave them some fruit flies that he raised on banana mush, in a little vial. You can buy the vials, flies, and dried banana flakes from a science supply company. Sleeve-cage too.

A vial of banana mush and fruit flies. You can see the flies on the side of the vial just below the sponge. Photo by Sally Kneidel.

Or you can catch your own fruit flies by putting a rotting fruit in an open jar on its side, outdoors. When the jar has lots of fruit flies in it, slap the lid on fast. Then put the jar in the refrigerator for a few minutes until the flies slow down. Then you can dump them into the cage with the hatchlings. For very small mantises, fruit flies are a good size. But as the mantises grow, they'll start to eat each other. That's the time to either separate them or release them outdoors.

Praying mantis egg cases are often sold as "natural pest control" for gardens. As indiscriminate predators, they go after any and all insects that are eating your vegetables. So let them go in the garden! Of course, you can't do this if you're using pesticides, which will kill the mantises too.

We'll be letting our little mantises go in our garden in a little while, after Ken has shared them with his biology classes. He uses them to talk about population growth, metamorphosis, predation and competition, ecological interactions between species, and so on. After we turn them loose, I hope they stay close by as they mature over the summer. If we're lucky, a few of them will survive to lay egg cases in our yard. And we'll get to repeat the treat of mantis hatching day next year too!

Male mantis eating. (Males are slender and fly.) Courtesy of

Adult mantis. Note spines on front legs for holding prey.
Courtesy of

For more info on raising mantises:

Sally Kneidel, PhD. Creepy Crawlies and the Scientific Method. Fulcrum Publishing.

Sally Kneidel, PhD. Pet Bugs. John Wiley & Sons.

Keywords: mantis praying mantis natural pest control biological pest control garden pests teaching metamorphosis teaching with mantises raising mantises mantis egg case Creepy Crawlies Pet Bugs Sally Kneidel fruit flies sleeve cage homeschool science lesson

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