Mantises: Predators in the insect world - News - Gondwana Collection


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Mantises: Predators in the insect world

Avatar of inke inke - 03. July 2018 - Environment

The African giant stick mantis grows to a length of almost 15 cm. This one with raised wings and forelegs is in the threat pose.

Dirk Heinrich

The well-camouflaged mantis sits on a flower motionless. Its splendid colours make for an excellent disguise. Unsuspectingly a bee comes buzzing closer. But before it has a chance to land on the flower, two spiky forelegs suddenly shoot forward, grab it, hold on mercilessly and the mantis starts to eat the bee. A little further on another mantis, camouflaged just as well, lies in wait among green leaves. A different species of mantis even sits on the bark of a shrub and waits for an insect or a spider to come within its reach. 

Mantises have extremely good vision and actually see prey in their vicinity. Some mantis species then close in very slowly and within a split-second suddenly take hold of the prey. Mantises use their forelegs, which resemble jack-knifes, for grabbing prey and holding on to it. 

There are 107 types (six families) of mantises in Namibia alone. They differ in size, shape and colour. Some, such as the leaf mantis (Phyllocrania paradoxa), look like a wilted leaf and others like the bark of a tree; the flower mantis (Harpagomantis tricolor) is almost invisible among the flowers it mimics, while the giant African stick mantis (Heterochaeta orientalis) grows up to 15 centimetres long and could be mistaken for a twig. 

A young African mantis. The nymphs are just a few millimetres long when they hatch. An adult can grow to more than 5 cm.

Some green mantises, like the giant mantis or common green mantis (Sphodromantis gastrica), wait among leaves to ambush their prey. But not only the prey has to watch out: the mates of the female praying mantis are also in danger. The females, usually larger than the males, are known to devour the male after mating, sometimes even during the act. 

A report published in July 2017 noted that praying mantises in 13 countries across all continents catch and eat small birds. According to observations 24 species of birds from 14 families are preyed on, e.g. hummingbirds in South and North America. It has not been established yet whether mantises in Namibia have been seen eating birds.

After mating the females deposit their eggs under cover of darkness in clusters enclosed by foam on twigs, bark or stones. The foam quickly hardens. In the ootheca (cluster of eggs) the nymphs develop and usually hatch after the winter or after the first rainfalls at the start of summer. The timing depends on the prevailing temperature and humidity. Many nymphs are disguised as ants at first, with the abdomen bent over the back. Eugene Marais, who worked as entomologist at the national museum for many years pointed out that temperature and humidity are important for eggs to develop and to stimulate the young mantis to hatch.

Like most insects the predatory mantises have many enemies. They are eaten by birds, reptiles and small mammals and they aren’t safe from their own kind either. Praying mantises are among the few insect species which are able to move their head, giving them stereo-vision in various directions. If they sense danger, some mantises, like the African giant stick mantis, not only rely on their camouflage but also spread their wings and raise their forelegs. 

The praying mantis is known as Oonamukokolambiga in Oshiwambo, Ousatana in Oshiherero and as Vakakurukadi in the Kavango regions; the Caprivians have named it Bonalunkalamba and the Nama and Damara people call it IIGâuagu.    

Some mantises have the shape and colouring of twigs and bark. Well-camouflaged and motionless they lie in wait on those lookalike twigs and bark until an unsuspecting prey animal approaches. The camouflage is also necessary, however, to protect the mantis from its numerous enemies.

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