The Praying Mantis/Mantids in our gardens.

by Alex Robles

Praying mantids have meant a lot of different things to different cultures over the centuries.  There was a time when the French thought that a mantis would point a lost child home. In some parts Africa it’s considered good luck if one of these alien insects lands on you.  The Greeks named them “Mantes”, which means prophet or seer. The Chinese write about the mantis curing all sorts of ailments, from goiters to impotence. They also believed that roasting the eggs cases and feeding them to children would stop bed wetting.  “But be careful not to eat the cases on an empty stomach for it will surely make one sick” is also in the Chinese

To me, the praying mantids are an awesome garden predator and an exciting part of nature.  There are about 2.300 species of mantid worldwide. They can be found on every continent except for Antarctica.  The places that have the most diversity of them will be the tropics of both the Eastern and Western hemispheres. About 20 different kinds can be found in North America and some of those can be spotted in the U. S.

Here are a few things you should know about the praying mantis before you release them in your garden.

What are They?  

  • The closest relatives of mantises are the termites and cockroaches.
  • They are masters of disguise and are typically green or brown, but some species will take on the color of their habitat.
  • They have been known to mimic leaves, twigs, grass, and even ants.  There are some tropical species that look some much like flowers that other insects will land on them in search of nectar.
  • Normally insects have ears on each side of the thorax, but the mantids have one ear that is located on the underside of their body between their legs.
  • Most adult praying mantids have wings (some species do not). Females usually cannot fly with their wings, but males can.
  • Mantids have two large compound eyes that allows them to be the only know insect to have stereo vision (Stereopsis) or 3D vision.
Praying Mantis – University of Kentucky

Note:  Each of our eyes sees a slightly different view of the world. Our brains merge these two views to create a single image, while using the differences between the two views to work out how far away things are.  Stereopsis is a term that is most often used to refer to the perception of depth and 3-dimensional structure based on the visual information gathered from two eyes.

  • Their vision is so good, they can spot the slightest movement from 60 feet away.
  • Those big eyes and that triangular head are perched on a long, flexible necks which bend easily.  That flexibility allows them to turn their heads 180° from side to side, giving them a 300° field of vision.
  • The two front legs of the mantids are highly specialized. When they’re hunting mantids assume a “praying” position by folding the front legs under their head. They use the front legs to strike out with lightning speed to capture their prey.  Long sharp spines on the under insides of these legs let them hold on to their victims. The impaled prey are held firmly in place while being eaten like corn on the cob. The spines fit into a groove on the lower parts of the legs when they’re not in use.
  • Praying Mantis are pure predator, they are not vegetarian in any stage of life.  They hunt and kill other living things. Other beneficial predators (lady bugs), other mantis, hummingbirds and some small lizards have been known to be on the mantises menu.  But they prefer the sucking and cutting insects, the ones that do the most damage to crops.
  • They are territorial hunters and will fight to death to defend their hunting grounds from other mantis.
  • They will also spend days waiting and stalking their prey.
  • Mantids natural enemies include birds, bats, spiders, snakes, and lizards.
  • Males are smaller than the females.
  • During mating the smaller male often jumps on the back of the larger female.  If the jump was successful, the pair mate. If he misses, he might become a meal for the femme fatale.
  • Females sometimes practice sexual cannibalism, during copulation (sex) the female might turn around, decapitate the male and devour his head.  The body of the male is capable of completing the mating, when complete the female will finish eating the male.
  • One of the reasons given for this, which is sited in old science textbooks, was that by severing the male’s head, it caused his muscles to contract and forced him to ejaculate sperm into the female.  This has been found not to be true.  One study concluded that females may decapitate males about 15% of the time when they mate.   Researchers believe that since it’s only about 15% of males are losing their lives, it’s not something that has to happen copulation to take place.  A better explanation for this is the fact that the mantis is an indiscriminate predator and kills him because she catches sight of him.
  • After mating, the female will lay groups of 12-400 eggs in a frothy liquid that turns to a hard protective shell.
  • The egg case is known as a “ootheca” and the nymphs hatch looking like smaller versions of the adults.
  • Small mantids emerge from this case in the spring, when the weather warms up to 70-90F and humidity is between 40-95%.  When hatching, the young crawl from between tiny flaps in the egg case and hang from silken threads about 2 inches below the case.  After drying out, the young will disperse. This happens within an hour or two. It is very difficult to know if hatching has occurred, unless the elusive and well camouflaged young are found.

Note:  I’ve never seen them hatch.  The first time I used them I thought I got ripped off, until I saw the tiny mantids hoping the garden.  I’m not sure how long they take to hatch.

  • Mature adults do not overwinter.  In the autumn the adult female will lay her eggs, then die.  Females frequently will wrap the egg cases around something thin such as a tree limb or twig or a fence wire, sometimes we’ll see them attached to the sides of houses.
  • The reason the egg cases have so many eggs is because only a few of the eggs will ever become mature mantids. For one thing, not all the eggs will hatch and sometimes wasps will prey on the eggs. Most of the eggs that do hatch will become prey for other insects, and sometimes brothers and sisters will kill and eat each other.
  • The young mantids will eat many different types of insects that are about their own size or smaller. They can eat their siblings when food is scarce as they are cannibalistic.  As they grow, they’ll be able to eat larger pray.
  • It takes an entire summer or growing season for mantids to mature to adulthood.

I love seeing praying mantids in my gardens, and I know they’re benefit.  I also know they are not the best general predator, mostly because they’re so cannibalistic and territorial.  Hanging lots of egg cases around the garden might not increase their presence because they tend to move away in search of food and cover.  Since mantids don’t eat plants, I’m not growing anything specific to attract them, but I am trying to make places for them to hide and hunt from.  That’s why I think they’re great for vegetable gardens. I also have to be able a tolerate a certain amount of pests in the garden to keep them interested in staying.  The praying mantis that I get from my local nursery are the “Tenodera sinensis” which are the Chinese mantis, which should be green and brown. Have fun in the garden.

Grow Learn Teach

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