Keeping praying mantids thriving indoors was a challenge that consumed Fran Bosi's elementary science students in Bayside, NY. Wanting to closely observe the creatures in the classroom, they had obtained mantid eggs from a science supplier during the winter when spring still seemed a remote possibility.
"We placed six egg cases that came on a branch into a container and added wet cotton balls for moisture," reports Fran. But when students came back from February break, they discovered that the young had hatched, then promptly eaten one another. "We tried again with a second set of eggs that we had refrigerated, and they hatched a month later," says Fran. "We discovered that if we kept containers with mantids replenished daily with fruit flies (which came with a rearing kit) and wet cotton, the insects refrained from eating each other."
With another vacation looming, Fran and her students decided to create a self-sustaining system by combining habitats for some of the predators and prey. They started by covering clear containers with a nylon stocking (to contain the insects) and plastic cling wrap over that (to retain moisture). Each container hosted fruit flies, yeast to feed them, wet cotton balls for moisture, and flower seedlings to provide oxygen for the live creatures. "Our system cut down on daily maintenance and seemed to keep the mantids alive and healthy," says Fran. The chambers also enabled students to routinely observe mantid antics and feeding behaviors, compare different individuals, watch them shed skin as they matured, distinguish the sexes (females have swollen egg-filled abdomens), then draw and write about their discoveries. "The kids were eager to release them into the school garden, but lost track of them before long," says Fran. No surprise. These non-picky eaters, who sneak up on a variety of prey, are well adapted to blend into the scene.
Fran recommends these books for enhancing mantid investigations for youngsters up to grade four: A True Book: Praying Mantis, by Larry Dane Brimner; Backyard Hunter: The Praying Mantis, by Bianca Lavies; Living Things: Praying Mantis, by Rebecca Stefoff.
Hatching Mantid Plans
Praying mantids readily captivate youngsters' eyes and imaginations. After all, they are cleverly constructed (and terribly efficient) garden predators. They can rotate their heads 180 degrees in search of food. Their specialized front legs that can fold under their heads (as though in "prayer") enable them to quickly strike out and capture prey. (Spines on the upper inside of the legs add to the insult!) These well-camouflaged consumers are generalists (they'll eat lots of garden creatures, including pests, other beneficial insects, and even each other), so they're not particularly good at cleaning up a breakout of any particular pest.
If you and your students have your minds on mantids, you can either get egg cases from a science supplier or look for them in your schoolyard. Students may be able to find foam-like cases containing eggs on twigs in late summer or early fall. (All adults die in the fall or early winter.) Have them put a twig with an egg case in a jar secured with a cloth lid and rubber band. Keep the jar in the refrigerator so the eggs won't hatch in mid-winter when it's too cold to let them go outside. Take the jar out in March or April when insects appear outdoors. Within a few weeks, 10 to 100 wingless nymphs, looking like miniature adults, will emerge. Be sure to release the young mantids immediately into your garden or schoolyard, so they won't eat one another ... then keep your eyes peeled.