The praying mantis: biological pest control
by LINDA MARRONE
Oct 13, 2008 | 5978 views | 2 2 comments | 11 11 recommendations | email to a friend | print
The praying mantis is a master of disguise. Although not hard to see on this leaf.
The praying mantis is a master of disguise. Although not hard to see on this leaf.
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It’s much more difficult to find her when she blends in among  other leaves and stems.
It’s much more difficult to find her when she blends in among other leaves and stems.
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Late last winter, I purchased a praying mantis egg sac for my garden. In all the years I’ve lived in San Diego, I’ve never seen a praying mantis in my garden, and I thought it would be fun to see how beneficial they might be. In recent years, my garden has been plagued with walkingsticks and grasshoppers that have a taste for every plant I grow. I was hopeful that if the eggs hatched, maybe the praying mantises would put a dent in the large pesky bug population in my garden.

I placed the mantis egg sac on a branch of a large camellia bush, leaving it encased in the plastic mesh bag it came in. The egg sac should be suspended from a branch, away from ants and hidden in the leaves from birds. It should also be kept outside to adapt to our climate, since the baby praying mantises will emerge from their sac in about three weeks after the outside temperatures reach around 70 degrees. In late June, I was working in the garden and noticed a tiny insect sitting in the center of a Shasta daisy. Since grasshoppers have been quite successful at raising their families in my garden, at first glance I thought it was a baby grasshopper. Luckily, I realized the ant-size insect was actually a baby mantis before the tiny creature ended up between my thumb and forefinger.

Each praying mantis egg sac encloses about 200 eggs. The tiny young that are referred to as nymphs will emerge from the sac, scatter into the garden and immediately begin eating.

They start off with a voracious appetite, eating aphids and other small insects, but when they are this small they also can fall prey to predatory insects. One day, I removed a tiny mantis from a hungry spider’s web just before it became lunch and placed it on a rose bush. As months went by, this tiny creature stayed on the same rose bush and has now grown into quite a specimen measuring about 5 inches long. Females are said to stay contently in one place as long as there is food and the males will wander here and there throughout the garden.

There are 2,000 species of praying mantis throughout the world, with about 200 of them living in the U.S. They will take about four to six months to mature, and as they grow they will molt and shed their skin, which prompted one of my gardeners to worry that the mantis had died. Clearly upset, he brought the empty skin to me, telling me that one of my new “pets” had perished. We went to look at the rose bush he found the skin in, and, sure enough, we found the mantis, now much larger and still sitting in her favorite bush. A mantis will shed its skin about five or more times during its growth period, and during the final molting, it will emerge with wings. Right now all of my praying mantises appear to have their wings, and we think there are about 12 of them happily living and feasting in my garden.

Territorial, each mantis will stake out its own area of the garden and it is rare to find more than one on a single plant, unless it is fall and the mating season has begun. They have 10 eyes that can see color and distances up to 60 feet away, and their heads can look over their shoulders, moving about 180 degrees. When I get close to them, they slowly turn their heads to look at me. Masters of disguise, the mantises’ green or light-brown coloring allows them to blend in seamlessly with their surroundings, which enables them to grab unsuspecting insects that venture too close. With a motionless prayer-like stance, the mantis can strike at its prey with lighting-fast precision, grabbing it with long spiky forearms.

Great to have in the garden, they feed on most harmful plant pests, including aphids, thrips, whitefly, mosquitoes, flies, grubs, beetles, caterpillars, leafhoppers, grasshoppers, crickets and, hopefully, walkingsticks. It may take another season to see if they are feeding on the pesky walkingsticks and if I find they are, I will let everyone know. The only problem may be that praying mantises are active during the day and the walkingsticks are nocturnal eaters. I am hopeful that if a walkingstick crosses paths with a praying mantis, the walkingstick will become a midnight snack. I have noticed fewer grasshoppers in the garden lately since the mantises have taken up residence.

Since they are not long-distance travelers, the mantises will live and die close to the area in the garden where they were born. In the fall, the female will lay her eggs and encase them with a liquid she produces that will harden and form the sac. Females can produce between one and five walnut-size sacs, or ootheca. Sadly, my family of mantis friends will die within the first year of their lives, usually about three weeks after their eggs have been laid. Hopefully next spring their eggs will hatch and the life cycle will begin again with a new family of mantises hunting in my garden.

Most nurseries stock mantis egg sacs in late winter and early spring, before the weather gets too warm. One egg sac is said to cover a 5,000-square-foot area. The praying mantis. along with other beneficial insects, helps to rid our environment of garden pests, and therefore it is essential to not use pesticides or they too will perish along with the unwanted bugs. A healthy garden has both good and bad insects, and by not using poisons we are promoting a healthy balance, not perfection, so all creatures, including humans, can thrive.

The Greek word for mantis means prophet, and maybe it was named because of the blessings your garden will have if they are found residing there, not to mention the good fortune of creating a cleaner, healthier environment.

— Linda is a local Realtor with Coldwell Banker who specializes in historic and architecturally designed homes. A co-founder of the Secret Garden Tour, you can find her working in her historic Barber Tract garden every chance she gets. Take a tour of Linda’s garden on www.LindaMarrone.com or call her at (858) 456-3224.
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josephlay
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May 29, 2014
Organic gardeners sometimes differ with each other when it comes about declaring mantises a good bug or bad. Well, this question makes no sense says some entomologists and many professional that i know in Roseville like "http://advancedipm.com/" as Mantises are like predators for beetles defoliating your wax beans.
gilmarlin
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December 09, 2011
In the last week there has been a large Mantis hanging out on my fence. I was worried that it would freeze in the weather we're having but it seems to be fine. I think maybe it laid eggs as it's body got smaller today, I'm looking for an egg sack but haven't found one yet. My wife bought an egg sack a few years ago and it hatched in the house before we put it outside :). It took us an hour to herd all the tiny babies outside, but they made it, so maybe the one I'm watching now is 2nd or 3rd generation...