CHAP. V.] COMMUNICATION AMONGST INSECTS. 47 



Chapter V. 

 COMMUNICATION AMONGST INSECTS. 



" Hast thou heard the butterflies, " Elappy the Cicadas' lives, 



What the) saj betwixt their wings ? " Kor they all ha wives." 



Tennyson Adeline. Xenarchus. 



THE simplest form of communication amongst insects is by the 

 production of sounds which may or may not be audible to human 

 ears but, except in the case of social insects, communication is 

 usually restricted to methods by which the sexes are brought 

 together or rendered attractive to one another. The hum caused 

 by the vibration of the wings or otherwise during flight, as in the 

 case of a Hawkmoth hovering before a flower, can scarcely be 

 considered as communication, similar sounds being produced by 

 other rapidly-vibrating bodies such as a spinning top or wheel. 



The shrill piping of Mosquitos and Midges and the chirping 

 song of male Crickets and Cicadas are familiar instances of sounds 

 produced by one sex in order to attract or charm the other. The 

 song of Cicadas, though often distressingly discordant to our 

 senses, is doubtless sufficiently pleasing to their voiceless females 

 and is astonishingly different from the shrill shriek of alarm emitted 

 by the insect when captured. 



Several of the long-horned green grasshoppers, commonly found 

 on plants and often attracted to light in the evenings, utter a very 

 shrill chirping and are further remarkable as possessing well- 

 developed auditory organs which may readily be seen on examina- 

 tion of their fore-legs. A similarly situated auditory organ is 

 found in many crickets and mole-crickets. In other insects the 

 auditory organs may occur on the antennae, abdomen or elsewhere. 

 The note of the hum of the female mosquito, for instance, causes 

 certain of the hairs of the antenna of the male to vibrate sympatheti- 

 cally so that, by turning his head until both antennas arc affected 

 equally, it is probable that the flight of the male is directed to the 

 female with considerable accuracy. 



It is impossible to enter here into the mechanism of the stridula- 

 tory organs of insects, i.e., of the organs which produce "song," 

 as these vary so greatly in different species. Usually the sounds 

 are made by the vibration of a membrane or the scraping of one 

 part over another, the latter generally being ridged. Stridulation 

 is not confined to grasshoppers or even to large insects ; some 



