The Praying Mantis and the Mantisfly

The Praying Mantis and the Mantisfly: Very Different Insects That Converge Body Forms

By Renn Tumlison,

Praying Mantis

The praying mantis is a familiar insect commonly seen in late summer and fall. It has a long body (about 7.5 cm, or 3 inches, in length), wings folded along the back, and two pairs of long legs used for walking or running. The front legs are modified into prey-grasping structures held in a position that reminds some people of prayer, and thus the common name. The head is triangular in shape and possesses large compound eyes. In contrast to most species of insects, the mantis can move its head around freely – about 180 degrees. This allows the mantis to look for prey, or danger, without having to move its green or brown camouflaged body. It can be an ambush predator, waiting for prey to move within striking distance, or it can run quickly to attack. The front appendages, known as raptorial legs, are used to seize prey. When at rest these legs fold into a “jackknife” position, but they are extended with amazing speed to grab prey. Spines along the leg help to hold captured prey. The mantis usually feeds during the day, but also will come to forage around artificial lights at night (usually these are adult males). Although some prey are stalked by the mantis, most are taken by “head-on” ambush. The mantis immobilizes captured prey by chewing on the neck first. Foods consist mostly of soft-bodied insects such as flies and moths. Often, a mantis will wait on a flower for insects that come for nectar. On occasion, a mantis may even capture and feed on a hummingbird that has come to a flower! A hungry female sometimes eats the head off of the male while they are mating. This cannibalistic behavior supposedly gives her a meal, and therefore energy for the fertilized eggs she soon will lay. Eggs are laid in a frothy material that eventually hardens into a foam-like structure called an ootheca that is attached to surfaces such as buildings or branches. The young all hatch at about the same time, looking like miniature adults. These young may begin to feed on each other, so it is useful for them to disperse quickly after leaving the ootheca. The praying mantis is considered to be a useful garden animal to help control other insects, so there is a market for them and their eggs. They generally do not bite humans, damage furnishings, or spread diseases.

The mantisfly is a weird insect that eats spider eggs then matures to look like a praying mantis. The strange insect called a mantisfly looks like a cross between a praying mantis and a common green lacewing - right photo - (to which it is more closely related). Adults reach lengths of up to 25 mm (one inch) long and are predators of insects. The mantis-like appearance is due to ecological convergence. Both of these insects are predators that stalk and quickly snatch their prey with the highly modified front legs, so those legs are built much the same way. Some species of mantisflies lay large numbers of eggs in several groups along leaves and stems where hunting spiders crawl. When the eggs hatch, the larvae reach up to catch a passing spider much like a tick tries to catch a passing mammal. Boarded spiders must be large enough that the mantisfly larvae are too small to be prey – otherwise they may be eaten. The larvae move to the pedicel of the spider (the joint connecting the abdomen with the rest of the body), out of reach of the spider’s legs. They may wrap around the pedicel like a belt and feed on spider blood at that site. Mantisfly larvae prey on eggs of hunting spiders, which explains the boarding behavior. Some species board female spiders and enter the egg sac while it is being constructed. If they board the female spider after the eggs already are being wrapped in silk, the larvae may get entwined and trapped in the silk of the sac. Initially, mantisfly larvae may board either male or female spiders as they are available. To be able to feed on eggs, however, they eventually need to be on a female spider. Larvae that happened to board a male spider can move to a female when the spiders mate, or in some cases when a female spider cannibalizes a male. Some species of mantisflies penetrate egg sacs already produced and placed in the environment, so don’t go through the boarding processes. In the egg sac, larvae use their modified mouth parts to pierce and consume the contents of the spider eggs. Larvae overwinter by staying with the host spider or the egg sacs, which themselves are in a safe place.

Mantisfly Combo
Weather Icon
Javascript must be enabled to view the current weather conditions