ARTHROPOD MUSEUM NOTES
Number 39 • October 26, 2005 • Jeffrey K. Barnes
Genus and species: Tenodera aridifolia sinensis Saussure
The Chinese mantid is a large species. Some individuals reach 3½ inches in length. They are variable in color, from brown to green, but most Arkansas specimens tend to be mostly brown, with green stripes along the leading edge of the front wing. The species has only one generation per year, and females die after producing eggs in the fall. As many as 200 eggs are embedded in a Styrofoam-like egg case called an ootheca. Well-fed females can produce four to six oothecae under ideal laboratory conditions, but in their American range, they rarely have time to produce more than one or two before killing frosts arrive. The eggs overwinter and hatch the following spring, with most eggs hatching simultaneously. However, eggs kept indoors will hatch, even without being subjected to a period of cold temperatures. Unless the nymphs are separated or well supplied with food, they will disappear one by one through cannibalism.
The Chinese mantid is widespread, and its ecology has been well studied. It can be found in a wide range of open habitats among many types of vegetation. It is native to most of temperate Asia, and it has attained a widespread but patchy distribution in the eastern United States. It is believed to have been accidentally introduced into the United States with imported plants around 1896, at which time it was found in Philadelphia. A nearby nursery was at that time receiving plants for all parts of the world. In the past century it has spread to form a contiguous range from southeastern New York to northern Georgia and from the Atlantic coast to the Mississippi River valley. Occasionally, individuals are found outside this distribution, even in areas where they cannot survive the winters. Females do not fly, but males may fly short distances. Individuals do not readily travel more than a few feet from their place of birth under their own power, yet the species has spread across the United States in the past century. Dispersal has been mainly through human agency, with eggs transported on vehicles and nursery stock and sold through the mail for biological control of insect pests.
Only a few individuals survive from egg to reproducing adult. Most mortality occurs in the early nymphal stages from starvation, predation, and desiccation. Eggs that hatch too early produce nymphs at a time when prey are scarce. Nymphs can consume pollen to prolong their survival until suitable prey can be found, but still only less than ten percent of individuals survive to adulthood. The rate of development is highly dependent on temperature and season length, which determine whether or not the individual will mature and reproduce before a killing frost. To a lesser extent, rate of development is dependent on food supply, but food limitation reduces fecundity.
Chinese mantids are opportunistic, generalist predators, taking virtually anything they can overpower, mostly other insects. In the entomological literature, there are at least two believable reports of Chinese mantids capturing and consuming vertebrates in captivity (soft-shelled turtle) and in the more natural setting of a flower garden (whitefooted mouse). In the latter case, a 3.0 to 3.5 inch mouse was captured by a mantid, which then began to consume the living mouse, starting at the nose and working back, eating hair, bones, and other tissues along the way. In the ornithological literature there are a least two reports of mantids, presumably Chinese mantids, capturing hummingbirds. Chinese mantids are well camouflaged and probably invisible to visually-oriented prey.
Studies have shown that sexual behavior in the male can be enhanced by decapitation, and the general public has become fascinated with the concept of sexual cannibalism in mantids. It is true that females sometimes consume their mates, but how frequently this happens is unknown. Mate consumption probably allows the female to mature eggs late in the season when other prey are scarce. Females that perch on asters and goldenrods have flower-loving insects at their disposal late in the season, and therefore they are at a reproductive advantage over individuals perched elsewhere.