Is the praying mantis a beneficial insect or a pest? A full analysis of its diet and lifespan

The praying mantis, also known as the dagger mantis, is an invertebrate and a carnivorous insect. Except in the polar regions, it is widely distributed throughout the world, with the richest variety of species in tropical regions. About 2000 species are known worldwide. About 147 species are known in China. So is the praying mantis a beneficial insect or a pest? What does it eat? How long is its lifespan?

Is the praying mantis a beneficial insect or a pest?

The praying mantis has a medium to large body, an inverted-triangular head, large and bright compound eyes, and slender antennae; its neck can rotate freely. Its body is yellowish-brown, grayish-brown or green. The thorax bears 2 pairs of wings and 3 pairs of legs; the prothorax is slender, and the front legs are a pair of thick, sickle-shaped grasping legs, with hook-like spines on the femur and tibia, used to catch pests, and so it is a beneficial insect.

The praying mantis has an elongated body, mostly green, though there are also brown or mottled species; the head is triangular and can turn flexibly; the compound eyes protrude, and there are 3 simple eyes; it has chewing mouthparts with strong mandibles. The front legs are grasping legs, while the middle and hind legs are suited to walking, with gradual metamorphosis. Eggs are laid inside an ootheca, with 20 to 40 eggs per ootheca, arranged in 2 to 4 rows. Each female can lay 4 to 5 oothecae; the ootheca is formed from a foamy secretion that hardens, and is mostly attached to tree branches, bark, walls and other objects. The newly hatched nymph is a “pre-nymph”, and molts 3 to 12 times before becoming an adult. Generally there is 1 generation per year, and a praying mantis lives about six to eight months; some species reproduce by parthenogenesis.

What food does the praying mantis eat?

The praying mantis is a carnivorous insect. It can prey on more than 40 kinds of pests, such as flies, mosquitoes, locusts, moths and butterflies and their larvae and exposed pupae, crickets and other small insects, and large insects such as cicadas, migratory locusts and katydids. It can serve as a natural enemy of pests such as aphids, greater wax moths, corn borers, cabbage white butterflies, ground beetles and yellow mealworms, and can destroy many pests in fields and forest areas, and is therefore a beneficial insect.

How does the praying mantis hunt?

The praying mantis has protective coloration, and some also have mimicry, resembling their surroundings, by which they prey on many kinds of pests. They are also agile, taking only 0.01 seconds to catch prey, eating only live insects, and holding their prey firmly with their spiny front legs. When startled, they rustle their wings and at the same time display vivid warning coloration. They are commonly found among plants rather than on the ground, and their body shape can resemble green leaves or brown dead leaves, twigs, lichen, flowers or ants; by relying on mimicry they can not only avoid natural enemies but also avoid being noticed when approaching or waiting for prey.

Appendix: The meaning of “the mantis stalks the cicada, unaware of the oriole behind”

The idiom “the mantis stalks the cicada, unaware of the oriole behind” satirizes those who care only about immediate gain and ignore the disaster behind them. It warns people who are short-sighted, blinded by greed, and heedless of future trouble, and it also likens people who scheme to harm others while not realizing that someone is scheming against them. Now let us take a look at this idiom together!

The original text of “the mantis stalks the cicada, unaware of the oriole behind”

The King of Wu wanted to attack Jing and told his attendants: “Anyone who dares to remonstrate will die!” Among his retainers was a young man who wanted to remonstrate but did not dare, so he hid pellets in his bosom and held a slingshot, wandering in the back garden until the dew soaked his clothes; he did this for three mornings. The King of Wu said: “Come here. Why do you trouble yourself so that your clothes are soaked like this?” He replied: “In the garden there is a tree, and on it there is a cicada. The cicada sits high, singing mournfully and drinking dew, unaware that the mantis is behind it. The mantis crouches and bends close, about to seize the cicada, unaware that the oriole is beside it. The oriole stretches its neck, about to peck the mantis, unaware that the slingshot and pellets are below it. These three all strive to gain the profit before them, without considering the trouble behind them.” The King of Wu said: “Excellent!” So he halted his troops.

The translation of “the mantis stalks the cicada, unaware of the oriole behind”

The King of Wu wanted to attack the State of Chu and told his ministers on the left and right: “I will kill anyone who dares to advise me against sending troops!” Among the King of Wu's attendants was a young man who wanted to advise the King of Wu but did not dare, so he hid pellets in his bosom and held a slingshot in his hand, wandering in the back garden until the dew soaked his clothes; he did this for several days. The King of Wu said: “You, why do you work so hard that your clothes are soaked like this?” The young man replied: “In the garden there is a tree, and on the tree there is a cicada. The cicada stays high, crying aloud while sucking dew, unaware that the mantis is behind it. The mantis bends its body and presses close with its front legs, wanting to seize the cicada, unaware that the oriole is beside it. The oriole stretches its neck, wanting to peck the mantis, unaware that the slingshot and pellets are below it. These three all certainly want to obtain the profit before them, without considering the hidden trouble behind them.” The King of Wu said: “Good!” So the King of Wu stopped the war.