If you find a praying mantis in your balcony garden, you may want to leave it there. Known as the praying mantis for its prayerlike stance, this insect is predatory and will feed on common garden pests. Many praying mantises are camouflaged, and you may not notice them.
The praying mantis is a biological form of garden pest control. You can even purchase mantis egg cases at some garden centers in order to release them into your container garden for organic pest control. Once the eggs hatch, the mantis nymphs need to eat a lot – they may actually eat each other if they don’t find enough aphids and other small insects. They can also eat beneficial insects, as well, including ladybugs. If you do want to introduce these interesting insects into your garden for pest control, realize that young will eat aphids, leafhoppers, mosquitoes, caterpillars and other small insects when young. As adults, they will consume larger insects, such as beetles, grasshoppers, crickets and other pests. The praying mantis will also feed on moths at night (this is the only predator that does this). You cannot eliminate all pests from the container garden with praying mantises. Absolutely never use insecticides around your praying mantis partner.
You may have heard that killing a praying mantis is illegal and subject to a fine. Even though you may rarely see a praying mantis, this is not at all true. It is an urban legend. There is only one species in the world (a Spanish species) that is listed as threatened. Other areas in the world may eventually list their mantises as threatened because of current habitat destruction. Mantises are not threatened in the United States.
Praying mantises will live for less than a year in your garden, and egg casings overwinter and hatch in the spring. Some people collect egg casings in the winter and keep praying mantises as pets in terrariums.