Praying mantids are exotic looking insects with a voracious appetite for almost any garden pest that they can overcome. The name "mantis" is derived from the Greek word for 'prophet' or 'soothsayer' and is descriptive of the manner in which they hold up the forepart of the body, with its enormous front legs, as though in an attitude of prayer. The praying mantis is in the family Mantidae, with a species name Mantis religiosa. Most species in the Mantidae family are similar, and of the species found in North America, most, especially the larger ones, found their way here on nursery stock from Europe in the late 1800’s. Mantis religiosa came from southern Europe, but we are probably most familiar with the large mantis sold commercially, the Chinese mantis, Tenodera aridifolia sinensis, originally from eastern Asia. Regardless of species, we tend to call all of them praying mantids (plural).
Praying mantids are at the top of the insect food chain. Being strictly carnivorous, they'll eat almost any insect of a size they can overcome. Mantids have enormous appetites, eating various aphids, leafhoppers, mosquitoes, caterpillars and other soft-bodied insects when young. Later they’ll eat larger insects – other mantises, beetles, butterflies, grasshoppers, crickets, spiders and other pest insects. They lie in wait for their food and when close enough, snap it up with a lightning movement of their strong forelegs - in a strike that takes only 50 to 70 milliseconds, one of the fastest muscle movements of any animal, more than two times quicker than houseflies.
It is the only known insect that can turn its head and look over its shoulder - they have a "neck" that allows the head to rotate 180 degrees while waiting for a meal to wander by. Their camouflage coloration allows them to blend in with the background as they sit on twigs and stems waiting to ambush prey. Mantids tend to be green or tan, and vary from three to six inches long. They have a triangular-shaped head with a large compound eye on each side. Their eyes are sensitive to the slightest movement up to 60 feet away. They also have ultrasound ears on their metathorax. Their straight, leathery forewings wings are well developed, but mantids commonly remain quiet in one place until another insect comes into reach. However, they sometimes cautiously stalk their prey.
Mantids live for a single season and are most commonly seen in late September and early October either resting on a plant or "fluttering" through the air, sometimes mistaken for a hummingbird. Praying mantids are most likely to be observed in the early morning or late afternoon, basking in the sunshine. During hotter periods of the day, they seek cover in shrubs, bushes and clumps of flowers where there is plenty of food and protection from predators.
In the fall the females produce 50 to 400 eggs in a large mass or cluster an inch or so long, within a frothy, gummy substance that turns to a hard protective shell (the egg case) and is glued to tree twigs, plant stems and other objects. The egg stage over winters in the case and will hatch into about 200 young mantids, tiny nymphs that emerge from the egg case in the spring or early summer. Once hatched, they immediately molt, and within about an hour the new skin has hardened and the nymphs begin to scatter to look for food feeding on small insects, such as aphids. Over the next three months, the nymphs will molt ten times as they develop into an adult. As they grow, they'll continue advancing up to larger and larger prey.
Praying mantids are territorial, although the size of the territory depends on the availability of food. They tend to stick around on one or two bushes throughout the season. A twenty by forty foot garden would support two or three adults at most. For the area they inhabit, they are likely to keep the local insect population down (both pests and beneficials), but since they don’t move around too much, their general benefit to your garden may be limited. You’ll need to consider whether you want to have these indiscriminate carnivores in your garden – they’re probably more garden good guy than bad. If you want to add these eating machines in your garden you can purchase egg cases and follow directions for their release. Rosemania.com/ is a good on-line source.
Praying Mantid photo by Marie Cheek, used with permission from: