IOWA ACADEMY OF SCIENCES. 195 



THE DOG-DAY CICADA. 



{Cicada tibicen Linn.) 



This is our larger common species, and one which, by its 

 penetrating note, renders itself a conspicuous feature of the 

 autumn weeks. First described by Liane it has since received 

 various appellations opercularis, Olivier; j^'^^uiiiosa, Say; lyricen, 

 DdGetr and canicularis, Harris. Tnis synomony arises partly 

 on account of the variability of the species. This variation is 

 considerable when its range over a large part of the United 

 States is considered, but within our own state this variation is 

 somewhat licnited. Specimens collected here generally conform 

 closely to the descripdon given by Say for his pruinosa. 



Its distribution is quite general and I assume that it occurs 

 throughout the eastern part of the state, at least, and in general 

 over the Timbered portions. I am assured by good observers, 

 however, that there are places in the northwest part of the 

 state where it is unknown. Specimens have been collected or 

 received from many widely different localities. 



In spite of its abundance and wide distribution our knowl- 

 edge of its habits and life -history is very meager, though it is 

 stated to require two years to complete its growth and to 

 deposit its eggs in apple trees as one at least of the plants it 

 may injure. 



THE PERIODICAL, CICADA OR "SEVENTEEN-YEAR LOCUST." 



{Cicada septen-decem Linn.) 



The "seventeen-year cicada" is doubtless the most interest- 

 ing of all the Cicadas on account of its phenomenally long 

 larval life. As is well known it lays its eggs in twigs of vari- 

 ous trees and the larvae entering the ground feed upon the 

 roots of plants, and require a period of seventeen years to 

 complete their growth. Tvvo broods are represented in the 

 state. 



Brood F, Distribution.^ln 188S, th^ locu5t year for the east- 

 ern part of the state, I secured, through the state crop service, 

 reports from many of the localities which gave decidedly use- 

 ful information with reference to limitations of the brood and 

 comparison with previous occurrences. Records were received 

 from over thirty counties and about ninety correspondents. 



The limits of this brood have been outlined heretofore by 

 Mr. Suel Foster, Dr. William LeBaron and Prof. C E. Bessey. 



