The Garden’s Beneficial Insects: Praying Mantis

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Not being temperamentally suited to dripping suitable hints, this female mantis gives the kiss of death to a star-crossed Romeo.

Here’s the fifteenth in a series of articles that will help you tell friend from foe in your garden. This issue is spent identifying a beneficial insect: praying mantis.

If you’re like most folks, you probably stoop occasionally
to inspect an insect. But how would you feel if the bug you
were looking at slowly turned its head and stared back
you? Well, the praying mantis can do just that. In
fact, when identifying the beneficial insect praying mantis, you will see it has the distinction of being the only
predatory insect that can swivel its head to look over its
shoulder. (The praying mantis is one species [Mantis
of the mantid family [Mantidae] and is also
commonly known as the praying mantid. Most mantid species
found in North America share the same general
characteristics and are often referred to as mantises.)

Additionally, the mantis is endowed with specially adapted
forelimbs that are held in a prayerlike position while the
voracious predator awaits its lunch. But, of course, this
namesake pose is just that . . . a pose. (As one
entomologist quipped, “The only thing mantids would seem to
pray for is a square meal.”) In fact, a mantid’s
forelimbs–rather than being hands designed for
supplication–are greatly enlarged legs that are lined
with sharp spines and can snap out with lightning speed to
snatch up a victim and hold it fast while the mantis
devours it alive. (All in all, highly irreverent behavior.)

In contrast to those outsized, raptorial forelimbs, the
four remaining legs are spindly. But no matter, really,
since the mantis doesn’t chase down its prey; rather, it
waits patiently in ambush for dinner to stroll or flutter
by. Since it’s not a picky eater, the mantis will gobble up
just about any sort of insect that happens along. Larger
mantids have even been known to tackle lizards and small
birds, and though they’re not generally aggressive toward
humans, some can inflict nasty bites if handled carelessly.

Members of the family Mantidae are long and slender, with
some species reaching four inches or more in length. Most
of the largest varieties, including the majority of those
sold for insect control, arrived in the U.S. by accident:
In 1899 they were brought in on nursery stock imported from
Europe. Despite its formidable size, the mantid’s green or
brown camouflage makes it extremely difficult to spot as it
sits motionless against a background of foliage.

During courtship, the male mantis must sneak up on the
female from behind, using great caution–for if she
spots him before he can grasp her, she’ll kill and eat him.
End of romance. But should the male be successful in wooing
his flame into mating with him, he may well have romanced
himself out of the frying pan and into the fire. The female
mantises, which are much larger than the males, will
sometimes bite the heads off their lovers–even as the
mating ritual progresses (talk about losing your head for
love!). Interestingly, though, removing the male’s head may
trigger even more aggressive mating (at least until the
bride gets around to finishing her meal).

When the time comes for the fertilized female to lay her
eggs (usually in the fall of the year), she seeks out a
small branch to serve as a nesting platform. With her eggs
deposited– usually in clusters of 80 to 100-mother
mantis covers them with a frothy secretion that dries into
a substance with a consistency something like Styrofoam.
Thus insulated against the cold and somewhat protected from
insect-eating creatures, the eggs pass the winter to hatch
the following spring.

The young mantids–which resemble adults except for
their smaller size, some subtle differences in coloration,
and the absence of visible wings–undergo a simple
metamorphosis by molting each time they grow too large for
their old skins. By late summer or early fall, the spring’s
mantid hatch is fully grown and ready to mate–thus
completing the life cycle.

As I mentioned earlier, mantids are advertised and sold
(generally by mail order) for the purpose of controlling
garden insects. The trouble is, while these hungry hunters
will indeed put a dent in your garden’s pest population,
they’ll also seriously reduce the number of
beneficial insects. (A mantis has never been known
to ask “friend or foe?” before snatching up and wolfing
down a passing bug.) Consequently, if you’re having
problems with a particular type of insect pest and wish to
try biological control methods, the best bet isn’t mantids,
but host-specific insect predators and parasites
purchased from a reputable insectary.

That’s not to say you should destroy any mantises you might
spot praying (and preying) in your garden, since a few
native mantids will do a garden’s ecosystem no harm, and
this shark of the insect world makes an interesting
addition to the backyard fauna. After all, how many other
insects have the gumption and ability to turn their heads
and look you right in the eye when you rudely stare at them
. . . much less the piety to “pray” before each and every