SB 



818 



C578 



ENT 



22, Second Seriks. 



United States Department of Agriculture, 



DIVISION OF ENTOMOLOGY. 



THE PERIODICAL CICADA IN 1897. 



There is perhaps no other American insect that has become more 

 famihar than the periodical cicada, otherwise known as the seven- 

 teen-year locust, or simply ' ' the locust. " Its appearance in enormous 

 swarms at long, regular intervals — 17 years in the more northern 

 and 13 years in the more southern parts of the country— never fails 

 to attract general attention. Its natural history has been so often 

 told that it is deemed unnecessary to repeat it here, and the object of 

 this circular is to invite the correspondents of the Division to send 

 word regarding the appearance of the cicada so that previous records 

 may be confirmed, the doubtful ones among them either verified or 

 rejected, and new localities made known. 



A knowledge of the exact extent of each swarm or brood of the 

 cicada is of considerable economic importance. It is well known 

 that the only damage inflicted by the cicadas is by hacking into the 

 terminal twigs of trees for the purpose of ovipositing, the twigs usually 

 dying within a week With large forest trees the damage amounts 

 to nothing more than a general trimming, and old orchards suffer 

 but little more, but on young fruit trees it tells very severely, and 

 instances are known in which newly planted orchards have been 

 entirely destroyed. Since there is in most parts of the country only 

 one brood of the cicada, injury to fruit trees is, therefore, expected 

 only once every 17 years (or every 13 years in the South), but there 

 are certain localities where two or even more broods are known to 

 occur, each appearing at intervals of 17 years (or 13 years in the 

 South), and where, therefore, damage to fruit trees may be expected 

 at shorter intervals. A knowledge of this fact, as well as of the 

 extent of each brood, would teach the orchardist not to lay out a new 

 orchard just one or two years previous to the expected appearance of 

 the cicadas. If this precaution has been neglected it is next to 

 impossible to prevent the cicadas from ovipositing in the branches, 

 especially when the orchard is in the vicinity of timber land. Still, 

 with particularly valuable trees it is practicable to protect them by 

 means of paper bags or muslin netting tied over the tops of the 

 trees. The duration of the danger from the oviposition of the cicadas 

 does not last longer than about three weeks, commencing in Ohio, 



