PRAYING MANTIDS — GURNET 341 



are so conspicuous, and the bodies of most species are so long and rela- 

 tively slender, that superficially there is little resemblance between 

 mantids and the broad and flattened roaches. It might be supposed 

 that, like roaches, mantids would have a long and ancient lineage 

 preserved in fossil beds dating far back in geological time. Such, 

 however, is not the case. Although ancestors of modern roaches 

 occur widely as far back as the Carboniferous, when coal was being 

 formed, fossil mantids have seldom been found, and then only in 

 the Miocene and Oligocene (according to Chopard, 1949), when the 

 evolution of the horse was moderately advanced and the age of dino- 

 saurs had long since passed. 



APPEARANCE AND ANATOMY 



Compared to most insects, mantids are relatively large, the more 

 conspicuous northeastern species usually being 2 to 4 inches long when 

 mature. The mantids living in the South and Southwest seldom ex- 

 ceed Zy2 inches in length, and there are several an inch long, or even 

 less. Mantids are elongate, relatively slender, and usually some shade 

 of green or brown. One individual may be green and another of the 

 same species brownish buff, while a third is partly green and partly 

 brown, this much variation occurring in the color of many species. 

 The most noticeable features are the front legs. Although the middle 

 and hind legs are slender and simply used for walking, running, and, 

 rarely, jumping, the front legs bear sharp spines and fold in a re- 

 markable hinged manner that enables the mantid to reach forward, 

 seize a fly or some other insect, and bring it to the mouth. In addi- 

 tion to seizing prey, the front legs are used to some extent for walking. 



Predatory front legs of this general type are not limited to mantids. 

 Front legs specialized for grasping prey have evolved in the Mantis- 

 pidae, a curious family of neuropteroid insects whose larvae usually 

 develop in the egg sacs of spiders, and certain raptorial families of 

 true bugs, such as the ambush bugs (Phymatidae) , show a comparable 

 development of the front legs. In each group the specialized fore- 

 legs differ in certain fundamental details, and it is evident that their 

 evolution has been along independent though parallel lines. 



The head of a mantid is triangular in shape when seen from the 

 front; the compound eyes are at the upper outer corners, and the 

 mouth opening is at the lower corner. Each compound eye is com- 

 posed of several hundred tiny facets, each facet receiving the light 

 from a fraction of the entire field of vision at one time. In addition 

 to the compound eyes, which are the most important organs of sight, 

 there usually are three ocelli. The latter are simple eyes, each of one 

 facet, which are arranged in a triad on the top of the head. They 

 supplement the compound eyes, enabling the insects to respond to 

 changes in light intensity better than when the compound eyes alone 



