38 APPLE TWIGS SEVENTEEN-YEAR LOCUST. 



washes are sure to be. The fibres of the tobacco, diffused through 

 this preparation, cause a portion of its strength to remain where- 

 ever it is applied, longer than any application which is wholly 

 soluble in rain water can do. He first trims the trees well, so 

 that every twig can be reached with the paint brush, and applies 

 this preparation before the buds have much swelled in the spring. 

 Two men, strictly charged to take their time, and be sure that 

 they painted the whole of the bark to the end of every twig, were 

 occupied a fortnight last spring in going over his hundred and fifty 

 young trees. When I saw his trees, the latter part of September, 

 this composition was still plainly to be seen upon the rough bark 

 of their trunks and upon the under sides of their limbs, resemb- 

 ling a whitish mouldiness of the bark. The trees had grown very 

 thriftily, and yielded well, whilst only a single scale could here 

 and there be found upon the twigs of the present year's growth, 

 all the older parts being entirely free from them. Although 

 trees perishing with lice were standing in the adjacent yards and 

 gardens, it seemed these insects preferred starvation at home 

 rather than being poisoned by invading these trees, hence it ap- 

 pears that one thorough application of this preparation is suffi- 

 cient to destroy all the insects upon the trees, and to protect 

 them from invasion from neighboring trees for a period of two 

 years; for free as the trees were from these insects in September, 

 there can be no call for a renewal of this composition upon them 

 the coming spring. 



"Wounding the twigs and causing them to wither and fall; a very largo 

 black fly with four glassy wings, with orange-colored ribs and red eyes. 



The Seventeen-year Locust, Cicada septemdecim, Linnaeus. 



On some accounts the Seventeen-year Locust is the most re- 

 markable insect of which we have any knowledge. The unusual 

 length of time which it requires for completing its growth, and 

 the perfect regularity with which every generation, numbering 

 many millions of individuals, attains maturity, so as to come forth 

 at the end of seventeen years, the entire brood hatching within a 

 few days' time, has caused this more than any other American 



