The Harvest Flies or Cicadas 



angles. The head has three ocelli placed triangularly on the 

 summit between the compound eyes and the antennae consist of 

 a short basal joint surmounted by a bristle which is divided into 

 about five segments. The tropical forms are sometimes brightly 

 colored but the species which occur in the United States are 

 usually greenish marked with black. 



The commonest form in the more Northern States is the so- 

 called "dog-day harvest fly " or "lyreman" — the insect which 

 every summer, toward the end of July or early in August, begins 



Fig. 124. — Eggs of the Periodical Cicada. 

 (After Riley.) 



its doleful but resounding buzzing hum in the tree tops. This 

 sound is familiar throughout the hot days of the late summer 

 and is frequently more noticeable in the early morning and 

 about sundown. This, however, may be due to the fact that 

 the day noises of a town or city are less noticeable at such 

 times. It is supposed that this is an annual species, i. e., 

 that it has but one generation annually, the larvae living in the 

 ground through only nine or ten months of the year. It may 

 be, however, that it has a much longer larval period, and that 

 only its great abundance and the intermingling of generations 

 accounts for its annual occurrence in the adult condition. 

 This is a point which should be investigated as its life history 

 has never been thoroughly worked out. There are other 

 cicadas in the Southern and Western States, some of them rather 

 small in size, like Tettigia hieroglyphic a, and others large, like 



the big Cicada emarginata. 



232 



