By Nancy C. Hinkle
University of Georgia
Only the youngest nymphs show any interest in very small insects, such as aphids, fruit flies and mosquitoes. Older nymphs and adults prefer to dine on moths, flies, beetles and larger insects.
Their green and brown bodies camouflage them well. The wings typically have markings that make them appear almost leaf-like. So disguised, a mantid is able to blend into the background and sneak up on unsuspecting insects.
BeastsBecause mantids are such good predators, gardeners are glad to have them around. As good as they are, though, no one claims they actually control pests.
They certainly contribute to the biological control that's going on in the garden. But because they're so cannibalistic, a garden can support only a few.
It's a bit like tigers. Each tiger has to have a huge home range to provide it sufficient food. And if the prey is reduced too much, the tiger is no longer able to find enough food for the effort it exerts.
It's the same with mantids. Even though they're large insects and each one eats a lot, no garden can support a huge mantid population. Each must have its own "turf" to avoid being eaten by another mantid.
Mantids are sensitive to most insecticides. Bacillus thuringiensis (Bt) and insecticidal soaps, though, won't harm them.
Tough loveA mantid's intent stare and habit of rotating its head to follow prey movement gives it an air of intelligence. Its head can swivel 180 degrees on its thin neck. That comes in handy for the female when she's mating.
The male mantid, which is smaller than the female, must approach the female cautiously, as any mantid will eat any other. So he approaches from behind and climbs onto the female's back, holding her with his front legs.
He then bends the tip of his abdomen around to join with the tip of hers, transferring sperm through her gonopore into a special chamber in her abdomen, where it's stored. These sperm then fertilize hundreds of eggs as the female lays them in several batches over the next few weeks.
The male's instinct to mate must be overwhelming. He commonly loses his head over it -- literally. The female's ability to rotate her head enables her to start eating the male's head even as their mating proceeds. The reproductive organs are able to keep transferring the sperm.
Once the male has contributed his sperm, the female finishes devouring him. After mating, his only value to her is as a nutrient source.
ProlificIn late fall, female mantids produce egg masses surrounded by a frothy covering that dries with the look and feel of foam-in-a-can. Each egg mass holds from a few dozen to several hundred eggs. The mantid glues the egg masses to plants or other structures.
In early spring, the nymphal mantids all emerge within a few hours. Any newly hatched mantids that don't immediately move away are eaten by their siblings.
Survivors live several months, growing larger and developing longer wings each time they molt. Females have expanded abdomens and eat large amounts of prey, so that they can produce several egg batches before they die.
So, despite the scientific name of one species, Mantis religiosa, mantids are more adept at preying than praying. Unless they're praying for prey. Or, for the females, praying for a mate-snack combo.
(Nancy Hinkle is an Extension Service entomologist with the University of Georgia College of Agricultural and Environmental Sciences.)