Meet Mantis

Eat, Pray, Love: The Insect Edition

Published online: Oct 05, 2020 Articles, East Idaho Outdoors Kris Millgate
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Your purple coneflowers are crunchy and tipping onto your porch, dropping seeds as they die. It’s time for a garden trim, but as you bend down to cut the dry stems, you find yourself eye-to-eye with a bug in praying stance. Preying is more like it. It’s a praying mantis looking for lunch in the evergreen bush next to the coneflowers. Pull your pruners, and your fingers, out of reach and watch the insect hunt. The mantis uses one ear and two 3D eyes to search your yard for food and mates. It’s eager for both in the fall, sometimes at the same time. 

Ear

A praying mantis is about 6 inches long. Much of that length is its long stick-figured body. The bug’s front legs are often folded in a pre-strike position, which ironically looks a lot like praying, thus the name praying mantis. 

Get past those commanding pinchers and you’ll find its ear. What it uses to hear isn’t on its head. A mantis hears with an ear that’s hidden on its chest. And what it hears is beyond our range. 

A mantis can hear ultrasonic pulses from bats that use echolocation to locate prey. When a bat targets a mantis for a meal, the mantis knows it by sound collected in its chest-centered ear and it can dive bomb away from a bat’s bite midflight. 

Eye

When you switch the bug’s position from prey to predator, eyes have priority over ears. Praying mantises have two large eyes. That’s not unusual. What is unusual is placement. Mantis eyes are on the same plane and forward facing on its face, like humans. This is unique in the bug world. Even more unique is the way a mantis uses eye placement to its advantage on a head that swivels 180 degrees. 

To study mantis vision compared to human vision, scientists at England’s Newcastle University used beeswax to attach mini 3-D glasses to mantises. One lens filtered for blue, the other for green. 

Our brain perceives depth by matching images sent from each eye. It’s called stereo vision. If those images don’t match, we see a blurry object. If those images don’t match in front of a mantis, it doesn’t care as long as there’s movement. Its depth perception is based on movement rather than matching images. That’s why a mantis pinches prey accurately and quickly. It’s ignoring all other factors and zeroing in on movement.

“They’re really good hunters,” says Jenny Read, Vision Science Professor at Newcastle University in England. “I always think about how terrifying it would be to be a cricket when a mantis is around.”

A praying mantis sees one thing moving in the crowd rather than the whole crowd moving and it targets that one thing as soon as it moves. Translating this visionary advancement beyond bugs could make simple robots more complex in the way they mechanically work in our world. For example, the floor sweeper that senses an upcoming wall and knows when to turn so it doesn’t run into the wall. Or how far to extend a robotic arm to pick something up. That’s mechanical depth perception. Studying mantis behavior helps improve that.

Eat

Zeroing in on movement makes a mantis an efficient eater and a deadly lover. From hoppers to birds, this bug eats well and well beyond what we expect. 

A researcher in India surprised the world with a fishing mantis. Rajesh Puttaswamaiah documented a mantis in his garden. More specifically, a mantis on a lily pad in the small pond in his garden. The mantis used the lily pad as its hunting platform while fishing for guppies. It caught and ate nine guppies in five days. 

“They’re amazing,” Read says. “They’ve achieved complicated behavior with such a tiny brain.”

Food is a major motivator for mantises in the fall. They’re on the prowl for prey as their one-year life winds down. They’re also looking for mates, sometimes in desperate fashion. Females are known to eat males during mating taking care of both needs at once. Harsh for humans, not harsh for nature. 

Outdoor journalist Kris Millgate is based in Idaho where she runs trail and chases trout. Sometimes she even catches them when she doesn’t have a camera, or a kid, on her back. Her first book ‘My Place Among Men’ is available now. See more of her work at www.tightlinemedia.com

Click here to read more of the November issue.


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