Prairie Incubator

Extraordinary beauty of marvelous design, intriguing purpose, and very amazing functionality. The hardened shell of a Praying Mantis ootheca evokes images of trilobite fossils. With spring in the air, I frequent such a mantis egg case attached to an old surveyor’s stake on the Llano Estacado--an autumn discovery. It faces east toward the rising sun and leeward of prevailing winds. I surmise the positioning has advantages.

In autumn a female mantis of the insect order mantodea lays between 10 and 400 eggs into a frothy mass secreted from glands in her abdomen. The protein foam hardens into a ribbed, protective capsule called an ootheca. Each rib of the honey-colored capsule has egg compartments. The mantis deposits the ribs in successive layers over several hours. The finished structure is about an inch-and-a-half long by half inch wide. Females attach ootheca to flat surfaces such as walls, fences, and house eaves; or to undersides of leaves, on twigs, and close to the ground on plant stalks. To protect the eggs against predators, such as parasitic wasps, they place the exquisite egg cases where they are difficult to see and are sheltered from winter weather. Her work is artistry. Her life cycle complete, she will die with the first hard freeze.

The controlled environment of the ootheca protects and hatches mantodea eggs within the layered compartments. Each cubbyhole has small one-way valve-like structures to help the insects hatch with minimum effort. Come spring the nymphs burst out like an army of ants. They are predators and immediately attack leafhoppers, aphids, small flies and grasshoppers. Their voracious appetite also leads them to cannibalize each other when suitable prey is not available. The likely genus and species of our mantid is stagmomantis carolina--Carolina Mantis. Their range is from the East Coast west to the Rocky Mountain States and south into Mexico.


© Ilija Lukić 2012

Mantis Ootheca