78 
THE PERIODICAL CICADA. 
plants, and are active usually in flight and often beautiful in form 
and color. The cicadas are not only the largest and most striking 
insects of their suborder, some of the species measuring over 6 inches 
in expanse of wings, but in the male sex are endowed with the power 
of song, which last characteristic has invested them with great pop- 
ular interest in all ages; and especially in the poetry of nature are 
they noteworthy, from the time of Homer to the present. 
The old genus Cicada is represented by species in all parts of the 
world, over five hundred distinct forms being already known, and 
the}^ are especially abundant in North America, nearly one hundred 
species having been described from the continent and adjacent islands. 
The more familiar of these insects to the popular mind are the com- 
mon dog-day cicadas, or 
harvest flies, represented 
b}' several species, the 
most abundant of which 
is, perhaps. Cicada tihi- 
cen L. {pruinosa Say). 
The sleepy droning of 
these annually appear- 
ing species in July and 
August is commonly 
taken as a harbinger of 
greater heat and is a 
most familiar character- 
istic of midsummer. 
The periodical species 
is much more slender 
and graceful than the 
majority of the annual 
visitors, but structurally 
is not very dissimilar. 
It is medium sized, for 
the most part black in 
color, with orange-red eyes and limbs, and with the margin of principal 
veins of the four nearly transparent wings similarly colored. 
In discussing the structure of this insect particular attention will 
be given only to the important organs, viz, those for taking food, or 
the beak, the instrument for piercing plants and depositing eggs, or 
the ovipositor, and the organ of song in the male insect. 
A cursory examination of one of these insects from above reveals 
its rather robust body, covered by two pairs of transparent parchment- 
like^ elliptical wings, which rest roof-like over the abdomen; the short 
transverse head, w itli great oval prominent eyes at the lateral angles, 
the three minute ocelli arranged in a triangle on top, and the very 
Fig. 31.— Head and prothorax of Cicada, lateral view, showing 
parts in normal position. For description, see fig. 33. 
(A.uthor's illustration.) 
