IOWA ACADEMY OP 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 Linne it has since received 
various appellations opercularis, Olivier; pruinosa, Say; lyricen, 
DfeGeer and canicularis, Harris. This 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 limited . Specimens collected here generally conform 
closely to the description 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. Two broods are represented in the 
state. 
Brood F, Distribution . — In 1888, the locust 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. 
