THE HOMOPTERA 189 



Some of the broods are more abundant and widely distributed than 

 others. Four are of sufficient importance to be mentioned. These are 

 Brood II, due in 1928 from Connecticut into North Carolina and at a few 

 scattered points to the west; the insects are quite abundant: Brood VI, 

 due in 1933, widely scattered over the country but not very abundant: 

 Brood X, due in 1936 from New York to Georgia and west to Michigan 

 and Illinois and at scattered points elsewhere, this being the most abun- 

 dant brood: and Brood XIV, due in 1923, from Massachusetts to Georgia 

 and west to Illinois; also an abundant brood. The important thirteen- 

 year broods are : XIX, due in 1924, from Iowa to Louisiana and eastward 

 to the Carolinas and Virginia, the largest of these broods : and Brood XXIII, 

 due 1928, from Missouri, Illinois and Indiana down the Mississippi Valley 

 with scattered colonies here and there to the east as far as Georgia. 

 This is also a large brood. 



Numerous enemies of the Periodical Cicada are known, many of them 

 being parasites. Some birds feed on them and a fungus causes disease 

 of the adults. Various mammals feed on them as they are coming out of 

 the ground. 



Control. In forests nothing can be done to control these insects, 

 but when they appear -in sufficient numbers in parks and orchards to 

 make treatment desirable, certain methods for preventing injury or for 

 the destruction of the insects are feasible. In some cases collection 

 of the adults by hand has paid. In others, spraying the tree-trunks 

 and other objects on which they rest while molting after leaving the 

 ground, aiming to hit as many of the insects as possible, and using a 

 strong kerosene emulsion for the spray material has proved quite effec- 

 tive, for where the cicadas are not killed they are crippled by the action of 

 the particles of the spray which strike them. This treatment, however, to 

 be successful must be repeated every evening about sunset or very early 

 in the morning before the insects begin to fly, as long as they continue 

 to come out of the ground. 



In the case of fruit trees anywhere, pruning is not advisable the spring 

 cicadas are due in that locality, until after the eggs are laid. Then, 

 pruning and burning the punctured twigs before the eggs hatch is desirable. 

 In some cases young trees suffer so severely that it is not advisable to 

 set out nursery stock the year before cicadas are due. Apple " whips" 

 however, can usually be safely planted the same spring that the cicadas 

 come, being generally too small to suffer much by the attacks of these 

 insects. Hogs allowed to run under trees known to have cicadas at 

 their roots will kill many of these pests as they come to the surface to 

 become adult in May and June of their seventeenth year. 



Various species of cicadas are common in nearly all parts of the United 

 States. In the East the Dog-day Harvest-flies (Tibicen linnei Sm. & 

 Grsb., and others) are often noticeable (Fig. 179), singing in the trees 



