1072 EXPERIMENT STATION RECORD. 



and climatic conditions several broods of both the 17-year and 13-year 

 forms Lave been definitely differentiated in time of appearance aud in 

 locality. The validity of 21 broods has been established. Of this 

 number 14 belong to the 17-year race and 7 to the 13-year race. The 

 periodical cicada is shown to be pretty generally distributed over the 

 country east of the Rocky Mountains. A detailed account is given of 

 the exact distribution of each brood and of the years when it has been 

 known to appear, and from these data predictions are made as to future 

 appearances of the different broods. In general the 13-year race is 

 shown to be southern and the 17-year race northern, but no arbitrary 

 boundary line can be established, for small broods of both races extend 

 over the dividing line. 



A long and careful account is given of the systematic position and 

 anatomical structure of the cicada. Its musical apparatus and song 

 are described, and the popular tales concerning the so-called sting of 

 the insect are considered. The author gives an elaborate account of 

 the occurrence, nature, and purpose of the cicada cones, of the trans- 

 formation aud emergence of the adult, and of the length of life of the 

 adult. In his account of the habits of the adult insect he says: "They 

 often also appear in greatest number in rather well defined districts 

 within the general range of the brood, or, in other words, are irregular 

 in local distribution. This variation in abundance is due in some cases 

 to differences in the character of the soil, and in other perhaps to vary- 

 ing surface conditions, as of timber growth, etc." 



The feeding habits of the adult cicada are described and an account 

 is given of various attempts to use the cicada for food. The author 

 names the plants upon which the insect deposits its eggs, and says that 

 a preference is shown for oak, hickory, aud apple. The process of ovi- 

 position is described in great detail. "The female," says the author, 

 "deposits the row of eggs on one side as she makes the original 

 cutting in the bark. She then moves back, and, swinging a little to 

 one side, inserts through the same hole the second row of eggs parallel 

 with the first, thus leaving a small bit of undisturbed wood fiber 

 bet ween the two rows of eggs." 



The normal period of incubation for the eggs is said to be from 6 to 7 

 weeks. As soon as the larva becomes free it "begins to run actively 

 about with the quick motions of an ant, but soon goes to the side of the 

 limb, loosens its hold, and deliberately falls to the ground." 



The experimental and other proofs of the length of the underground 

 larval and pupal life are enumerated and discussed. Four larval stages 

 and two pupal stages are distinguished and described. The root- 

 feeding habit of the larva is described in some detail. The larva? are 

 said to occur in greatest number at a depth of from 8 to IS in. in the 

 soil. The damage caused during the underground life of the insect is 

 considered very slight. 



Among the natural enemies of the cicada are mentioned reptiles, 

 quadrupeds, birds, ground beetles, dragon flies, soldier bugs, hogs, and 



