By Nancy C. Hinkle
University of Georgia
The praying mantid holds its forelimbs folded in front of it, as
if in prayer. If it’s praying for prey, it’s well equipped. Sharp
spines on these “praying” legs impale other insects and hold them
while the mantid enjoys its meal.
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Mantids are voracious garden predators. They eat many kinds of
pest insects. The larger ones have even been said to catch and
eat lizards and hummingbirds.
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.
Beasts
Because 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 love
A 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.
Prolific
In 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.)
