View from the Garden: Praying Mantises Are a Sign of a Healthy Garden

Praying mantis chomps down
Praying mantis chomps down. Photo credit: Fuse/Thinkstock

My husband is a “birder” and also an “insecter.” He goes out to “shoot birds” (with his camera) at least once a day, he monitors our bird feeders and he goes into the garden several times throughout the day if he sees something interesting there that needs to be “shot.” He is dedicated! He recently spotted a praying mantis in the buddleia. He checked on it several times, and at one point saw it eating a monarch butterfly. Monarchs are becoming endangered, and so he was not very happy with the mantis.

My two gardening co-workers don’t like praying mantises (they are afraid of them, I think) and they want to kill them until I lay down the law. (They also want to kill garter snakes and here the laying down of the law is also required.) I think it’s because the mantises look so strange, are very large compared to other insects, and because mantis females eat their mates. But I have read that mantis females in the wild eat their mates only about 30% of the time. That’s not so bad, right?

Mantises are formidable predators though. They have large compound eyes that see color and two simple ones in a triangle between them that see light and dark. Their heads can turn 180°. They hear the ultrasonic sounds of bats. They camouflage themselves to look like the plants in which they lay to ambush a bit of prey—prey that they snatch with their praying legs so fast it is hard to see. They have no venom but instead eat their dinner alive.

We buy mantis egg cases at the garden centers and assume that they eat only the bad insects, but they also eat beneficials. They will eat a native bee or a monarch butterfly as easily as a moth, grasshopper, cricket, or fly.  They sometimes eat other mantises.

I love to see them in the garden, though, because their presence indicates many insects in the garden and therefore a rich and healthy ecosystem. This makes me feel like a responsible gardener. A balanced garden has good and bad insects. The goal is to keep the bad ones in check.

In September and October, mantises lay eggs in a case called an ootheca. It is a small, light-brown sack-like structure on a twig and looks like no other insect egg case. Do not take it into your house to investigate because the warmth of the house will cause the eggs to hatch, and you’ll wind up with a bunch of baby mantises in your house.

My husband came home very excited from fishing one day. The inside of his pickup was covered with baby praying mantises, which are about a quarter-inch-long and have the same body as adults. My husband thought he had been blessed by nature and that she trusted him enough to have these babies congregate in his truck. I went out to see them and at that moment realized that I had forgotten an egg case that I bought at the garden center and left in his truck. He was disappointed. The babies were so wonderful we opened the doors and watched for a long time until they had moved on. That is probably the only time I will see baby mantises, because they are so small and they disappear into the plants where they are born. So I guess we were blessed by nature. I feel blessed by nature every time I see a mantis in a shrub.

I also recently saw a small lizard scurrying under the plants in the garden. Talk about a healthy garden!

Jeanelle Myers is a professional gardener, landscaper and consultant. For gardening discussion you can call her at 631-434-5067.


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