PRAYING MANTIDS — GURNET 349 



An equal amount of the matrix is placed each side of the central sec- 

 tion where the eggs are located. The top of each layer is finished in 

 such a way that the final product is characteristic of the species, and 

 the lower end is smoothed off when egg deposition is completed. 

 Within an hour the matrix is reasonably dry and has a spongy texture. 

 Though nearly white at first, darkening soon begins, and within a 

 week or so the gray or brown color typical for the particular species 

 is the rule. 



Egg-laying by our best-known species most often occurs late in the 

 day and frequently after dark. Females do not look around during 

 the oviposition process but are guided by instinct and the sensory 

 organs located at the end of the abdomen. To me the ability of each 

 species consistently to produce its own characteristic type of ootheca, 

 although superficially equij)ped with the same type of ovipositing 

 organs, is one of the most remarkable characteristics of mantids. 

 Doubtless for thousands of years each species has passed this ability, 

 mainly expressed in blind but unerring instinct, down to succeeding 

 generations. Such is the nature of species, each difi^ering from others 

 in definite, though not always grossly conspicuous, ways. 



FLIGHT AND OTHER METHODS OF DISPERSAL 



Most fully winged mantids occasionally fly, the flights varying in 

 extent from a few yards to several hundred yards or more. Females 

 approaching the time of egg-laying are usually quite heavy-bodied, 

 since the abdomen is filled vvdth eggs, and in that condition they are 

 not so inclined to fly as during the first 2 weeks or so after maturity 

 is reached, nor so apt to fly as the males. Mantids are sometimes at- 

 tracted to lights at night, with the result that they are found near 

 windows the following day. Specimens have been found at the top 

 of the Empire State Building in New York City. 



The natural spread of a species of mantid into territory not previ- 

 ously occupied is by flight, in the case of winged species, and by 

 crawling. Many years may thus elapse before a species travels more 

 than a relatively few miles. Occasionally winds may add greatly to 

 the distance covered by a mantid in flight. Artificial transportation 

 by human agencies has in modern times become rather important in 

 the dispersal of mantid species to areas where they did not originally 

 live. Such introductions are largely by means of the egg masses, 

 which are often unintentionally carried attached to shrubs, hay, lum- 

 ber, or other materials. Notable examples of artificial introductions 

 are the three mantids established in the Hawaiian Islands, two of these 

 from the region of the Philippines and China, the other from Aus- 

 tralia or thereabouts. One of them, the narrow-winged mantis, has 

 also successfully entered the United States and, like the European and 

 Chinese mantids, has become acclimated here. 



