SUMMER MEETING AT BROOKFIELD. 155 



and other interesting characteristics what they lack in number of spe- 

 cies. These are the cicadas or harvest flies, famous even in classic 

 times for the rattle of their kettle drums, which may be heard, under 

 favorable conditions, at a distance of a mile. 



Of these insects we have in this country three or four annual spe- 

 cies, besides the anomalous periodical or 17-year species — incorrectly 

 termed the " 17-year locust." They are all large insects, with a broad 

 head, pominent eyes, sharp, strong beak and glossy net-veined wings 

 which close roof-like over the body. 



They feed entirely on vegetable juices, and their larvae, which are 

 grub-like, but with strong, spiny fossorial legs and a distinct head and 

 thorax, live under ground upon the sap of roots and upon moisture ex- 

 tracted from the earth. After changing to pupre they gradually work 

 their way upward to the surface of the earth, and upon emerging crawl 

 up the trunk of the nearest tree, where after a short rest, the back 

 splits open and the perfect winged insect is disclosed. The pale brown, 

 semi-transparent pupae shells are often seen during summer attached 

 to the trunks of fruit or shade trees. 



In these insects the musical organs consist of a pair of drums, sit- 

 uated on the basal joint of the abdomen, just back of the wings. In 

 the periodical species they are quite conspicuous, but in the annual 

 species are concealed in the cavities under valves, which have to be 

 cut away in order to conveniently examine them. Their structure is 

 unique and beautiful, and I cannot describe it better than in the words 

 of Dr. Harris, one of the pioneer entomologists of America. The musi- 

 cal instruments "are formed," he says, " of convex pieces of parchment, 

 gathered into numerous fine plaits lodged in cavities. They are played 

 upon, not by sticks, but by muscles or cords fastened to the inside of 

 the drums. When these muscles contract and relax, which they do 

 with great rapidity, the drum-heads are alternately tightened and 

 loosened, recovering their natural convexity by their own elasticity. 

 The effect of this rapid tension and relaxation is the production of a 

 rattling sound like that caused by a succession of quick pressures 

 upon a slightly convex and elastic tin plate. Certain cavities within 

 the body of the insect, which may be seen by raising two large valves 

 beneath the abdomen, separated from each other by thin partitions,, 

 having the transparency and brilliancy of mica, tend to increase the 

 vibrations and add to the intensity of the sounds." 



It is the males only that are thus endowed, the females having no 

 power of making even the faintest rejoinder. This fact seems to have 



