CICADA 
33 
injure apple, cherry, and peach trees, and the cabbage plant. 
The several kinds of scale insects which harm orchards may 
be killed by spraying the trees with a solution of lime and 
sulphur. 
19. Cicada. — One of the most interesting insects of the 
Hemiptera is the seventeen-year cicada (si-ka'da), com¬ 
monly called the “ seventeen-year locust.” The name is 
given to it because the nymphs (nim'fs, the immature stage) 
remain in the ground, actively feeding on roots, for seventeen 
years. There is another 
kind of cicada that re¬ 
mains in-the ground for 
thirteen years. 
Every thirteen or 
seventeen years, gener¬ 
ally in the month of May, 
the nymphs crawl out of 
the ground, climb trees 
or fences, and molt into 
adult cicadas. The adult 
females lay their eggs in 
tender shoots of trees, 
causing the shoots to die. 
The young cicadas, after 
hatching in the shoot of 
the tree, go into the 
ground and begin their 
long period of larval existence which lasts thirteen or seven¬ 
teen years. These cicadas are usually found in limited 
areas, but in these areas are very numerous. 
The cicadas which we hear every summer are another kind, 
whose nymph lives in the ground for two years. As there 
are two broods of this species that appear in alternate years, 
the number does not seem to vary from year to year. Birds 
do much towards destroying them, the kingbird, sparrow- 
Figure 17.— Adult Seventeen-year 
Cicada and Nymph. 
These insects, commonly called locusts, 
were abundant in the early summer of 
1919 in the Eastern and Middle-Western 
States. Did you see any of them ? If 
you did not, you will have to wait seven¬ 
teen years before you have another 
chance. There may be other breeds in 
the vicinity. 
