How to Kill a Mantis

With its spiked, raptorial front legs, its creepy ability to follow movement with a 180 degree head rotation and its reputation for cannibalizing its mates, it might seem like a good idea to get rid of a menacing mantis from your garden. But the praying mantis is a helpful predator to have around because it keeps pest insects from damaging your plants. Resist the urge to kill this beneficial insect and consider moving it out of your sight. If you simply can’t tolerate a mantis in your garden, collect it then choose a killing method that suits your comfort level and prevents disruption to surrounding plants, soil and other garden creatures.

Mantids have quick reflexes for grabbing crickets or other fast-moving prey, but they are typically clumsy fliers and easy to capture. Although they are capable, mantids don’t usually bite when handled. Collect the mantis in your hands or by nudging it into a box, glass jar or plastic container with a tight-fitting lid. Don't use a container that the insect can chew through, such as a plastic bag.

If you’d rather not encounter this insect while tending your plants, move it to a suitable location where it can still do its job but is out of your sight. The European mantis (Mantis religiosa), an introduced species now well established throughout the U.S., is pale green, about 3 inches long, with black and white bull's-eye markings on its inner front legs. It camouflages well on like-colored plants in your garden including shrubs and flower stems. It prefers areas with mixed vegetation. The Chinese mantis (Tenodera aridifolia), another introduced species, grows up to 5 inches long and is typically light brown in color. The Carolina mantis (Stagmomantis carolina) is also light brown but is a smaller species at approximately 2 1/2 inches. The Chinese and Carolina mantids prefer meadow habitats.

As temperatures begin to drop before winter, female mantids lay eggs in a hardened, foamy, protective casing that protects the eggs until spring. The adults then die off. If you are unable to introduce your mantis into another location, you can kill the insect by freezing. After collecting it, put the jar containing the mantis into your freezer. This nontoxic method mimics the conditions that the insect typically experiences before winter. After a day or two in the freezer, dispose of the mantis in the trash.

Used by entomologists in the field for collecting insect specimens without harming surrounding plants and animals, kill jars quickly kill insects with little trauma. Place a 1-inch layer of absorbent material, such as sawdust, cotton or newspaper strips, into a wide-mouthed jar with a tight-fitting lid. Pour enough ethyl acetate -- nail polish remover -- into the jar to thoroughly dampen the material. Seal the jar until you are ready to collect the mantis. Once you have found the mantis, remove the jar’s lid, being careful not to inhale deeply. Nudge the insect into the jar then quickly replace the lid. After the mantis dies, dispose of it in the trash or compost.

To prevent encountering a mantis in your garden, look for egg cases in late summer or fall. The cream-colored, foamy masses can usually be found attached to tall grasses or plants. Cut the stem containing the egg case and move it out of your garden or dispose of it in the trash.