INSECTS
the eggs into the twigs of trees and bushes. Ordinarily the ovipositor is kept in a sheath beneath the rear half of the abdomen, but when in use it can be turned downward and forward by a hinge at its base (Plate 7). The ovipositor
Fig. 119. Males of the large and small form of the periodical cicada (natural size)
consists of two lateral blades, and a guide-rail above. The blades excavate a cavity in the wood into which the eggs are passed through the space between the blades.
It was formerly supposed that the periodical cicada takes no food during the brief time of its adult life, but we know from the observations of Mr. W. T. Davis, Dr. A. L. Quaintance, and others and from a study of the stomach contents made by the writer that the insects do feed abundantly by sucking the sap from the trees on which they live. The
Fig. 120. A male of the periodical cicada with the wings spread, showing the ribbed sound-producing organs or tympana (Tm), on the base of the abdomen
cicada, being a near relative of the aphids, has also, as we have already noted, a piercing and sucking beak by which it punctures the plant tissues and draws the sap up into its mouth. Unlike the other sucking insects that infest plants,
[ 200 ]
