Bugs, Cicadas, Aphids, and Scale-insects 167 
life of but one or two years. But few species of cicadas, dog-day locusts, 
harvest-flies, or lyremen, as they are variously called, occur in this country 
—they are more abundant in subtropic and tropic countries—but their 
large, robust, blunt-headed body, their shrill singing and their wide dis¬ 
tribution make them familiar insects. 
In summer and fall the piercing, 
rhythmic buzzing of the cicadas comes 
from the trees from early morning 
till twilight. The song, unlike that 
of the katydids and tree-crickets, is 
hushed at night. The sound is made, 
not by a rasping together of wings 
or legs, but by stretching and relaxing 
a pair of corrugated tympana, or 
parchment-like membranes, by means 
of a muscle attached to the center 
of each; much, indeed, as a small 
boy makes music from the bottom of 
a tin pan with a string fastened to its 
center. These sound-making organs 
of the cicadas, confined to the males— 
Fig. 235. — The seventeen-year cicada, 
Cicada septendecim; specimen at left 
showing sound-making organ. v.p., 
ventral plate; t. } tympanum. (Natural 
size.) 
“Happy is the cicada, since its wife has no voice,” says Xenarchos—are 
situated in resonance-cavities or open boxes, furnished with other sym¬ 
pathetically vibrating membranes, at the base of the abdomen (Figs. 235 
and 236). The sound-chambers are incompletely closed (wholly open in the 
seventeen-year cicada) by a pair of semicircular 
disks, which are opened s or shut bv move¬ 
ments of the body so as to give the song a 
peculiar rhythmic increase and decrease of 
loudness. 
The cicada that is most familiar, and on hand 
every summer over most of the country, is the 
large (2 inches in length to tip of closed wings) 
black and green dog-day harvest-fly, Cicada 
tibicen. The life-history of this species is not 
fully known, but the insect requires, accord¬ 
ing to Comstock, two years to become mature. 
The really famous cicada is Cicada septen¬ 
decim , the seventeen-year locust, or periodical cicada (Fig. 235). It is 
about ij inches long, black, banded with red on the abdomen, and with 
bright red eyes and the veins of both wings red at the base and along the 
front margin. The females lay their eggs in early summer in slits which 
Fig. 236.—Diagram of section 
of body of cicada, showing 
attachment of muscles to inner 
surface of sound-making 
organ. (Enlarged.) 
