General Information about Mantids
Collectively these insects are sometime referred to as ‘mantis’ and sometimes as ‘mantids’ in order to distinguish the collective name from that of the genus Mantis. They belong to a superorder of insects called the Orthopteroidea which includes grasshopper, crickets, stick insects, mantids and their closest two relatives the cockroaches and termites. They are part of the larger group of insects whose young are in the form of nymphs which resemble small wingless adults. The young in the other group are in the form of larvae which do not resemble the adults and adopt a dormant, incubation phase called a pupa before becoming adult; this group includes butterflies, flies, wasps and beetles.
The eggs of mantids are encased in a package called an ootheca. These are laid as a foam-like substance which hardens into distinctive shapes. [Various ootheca are shown on some other pages]. The larger ootheca can contain up to 70 or 80 eggs but the smaller ones usually 15-30. They are normally laid either on the side or underside of rocks or on twigs but some species like Rivetina baetica lay them in soil [see also Wieland, Millage & Svenson]. In parts of Spain the oothecas, particularly those of Mantis religiosa, are called ‘sinbúscalo’ and are believed to cure tooth ache [González & Cruz-Sánchez]. The newly-hatched nymphs may be only 2-3mm in size, and can have up to 10 moults before they become adult. The stages between moults are called instars.
The early instars do not have any apparent wings but the later ones have unexpanded wings within the transparent membrane on the side of the upper abdomen; these are called wing-buds. The wings of adults vary in size according to species. For instance, Apteromantis aptera has no wings but some of the Amelidae, particularly the females, have shortened wings, whereas male Ameles and some of the larger species like Mantis religiosa and Iris oratoria have fully developed wings which stretch beyond the end of the abdomen. Adults, particularly the females, will take 10-15 days to reach sexual maturity in the smaller species like Ameles, though larger species like Mantis and Sphodromantis may take up to 35 days. Mature females will ‘call’ to the males chemically by releasing pheromones, usually after dark although a few species like Ameles spallanzania call in the afternoon. Females may lay several ootheca.
So the life cycle of a mantid is: egg – nymph – adult [which then lays eggs]. The length of each stage in this cycle can vary considerably from species to species as well as within some species and this in turn determines the number a generations that may occur within a year. In some species like Mantis religiosa and Iris oratoria this never appears to vary. They have a single generation a year, over-wintering in the egg stage and becoming adult in late summer. However, in some of the smaller species like the Ameles the number of generations in a year may vary according to the weather in any year and the altitude or the latitude in which they live. At times, this may cause generations to overlap. For instance, in some years in southern Spain, it is possible to find adults or nearly-mature nymphs along with medium-sized and newly-hatched nymphs of Ameles picteti at the same site during the autumn. None of the mantids over-winter as adults, though Sphodromantis viridis may be found well into the winter, as late as January. However, a number of the Ameles will pass the winter as nymphs to become adult March and April and then have a second generation in the late summer. Conversely, Empusa have a single annual generation, spending the winter as nymphs to become adult in May or June.
Female mantids have a commonly-known reputation for eating the males when they mate but the extent of this varies from species to species and other factors such as how well fed they are will also influence their tendency to cannibalise. For instance, female Ameles picteti cannibalise much less frequently than those of Ameles spallanzania do. Males will continue to search for the female’s genitalia with his as she eats him and will often manage to mate with her as as he is consumed, starting with the head and finishing with the end of his abdomen. In recent years much research has been carried out on the behavoural relationship and motivation of each sex at the time of mating but these are still not entirely clear and may vary between species.
Mantids live in a variety of habitats particularly in grassland, scrub of various sizes and trees but there are also ground-dwelling species like Geomantis larvoides. Mantids are very cryptic insects, blending in with the background of their habitats so that grassland species like Ameles picteti are slender and patterned with bands of shading along the body and are either beige or green in colour depending on the state of the grassland. The more tree and large shrub-based species like Sphodromantis viridis are usually a shade of green blending in with the leaves. These species will often rock backwards and forwards or side to side when they move which helps to blend them in with the movement of the vegetation – a behaviour also seen in the Chameleons. Being cryptic not only helps them avoid being noticed by potential predators but also by their prey. Mantids that live in vegetation tend to wait for their prey or creep slowly up on their prey and then pounce on it. The ground-dwelling mantids which are usually brown or grey in colour are much more ‘rush and grab’ predators, waiting for their prey in the cover of the leaf litter and underbrush around the shade of woody plants.
The bodies of mantids have not only evolved to be cryptic but are also adapted to their type of prey and the manner in which they capture it. Ground dwelling species like Geomantis and Revitina have long legs which permit them to be agile, fast runners; but whereas the more robust forelegs of Geomantis are adapted to catch small, ground-dwelling invertebrates, those of Revitina are long and thin to accommodate the catching of larger, flying insects like butterflies. The females of Ameles spallanzania are slow-moving preferring to position themselves where sufficient prey will come to them. They have very robust forelegs which allows them to trap insects at least twice the size of their head and occasionally almost their own size.
If predators – or other mantids – get too close, mantids may resort to what is called a ‘deimatic display’ when they make themselves look large and fierce by standing up high on their mid legs with their forelegs wide apart and the wings spread. In some species pseudo eye patterns are also displayed on their hind wings. This behaviour is most aptly seen in Iris oratoria – see top of home page. The spot on the fore coxae of Mantis religiosa may play a similar role.
Mantids have eyes that can adapt to both day and night vision because in many species the males find the female and mate at night. In those species with winged males this may involve flying when they can fall prey to bats. To help avoid this fate, the mantids have an ear which is situated on the underside of the body between the legs and which is tuned to pick up sounds within the range of the bats’ ultra-sonic calls.
In the animal and plant world there is a phenomenon called convergent evolution. This occurs when totally unrelated animals live in similar ecological niches and so have evolved to look similar. This is aptly demonstrated in Spain by species of Mantispa which are quite mantid-like in appearance. Mantispa are insects within the order Neuroptera which includes lacewings, antlions, serpent flies and ascalaphus [which look a bit like dragonflies]. They are quite unrelated to mantids.