INJURIOUS INSECTS. 305 



or part of viae to another, and in the autumn to the plant upon which 

 they are taught by instinct they can pass the winter in comparative 

 safety. 



They are found in greatest abundance on the newest and tenderest 

 growth which the irritation of their innumerable punctures and their 

 abstraction of the sap, causes to turn yellow and die back, sometimes 

 for eight or ten feet, the result being to greatly diminish the quality 

 and quantity of the frait product, even where the vine is not killed 

 outright. The area of the country in which this pest has established 

 itself has increased very rapidly within a few years, and unless measures 

 are taken to suppress it, or natural checks develop, it threatens all the 

 profits that have heretofore been made from the culture of cucurbi- 

 taceous plants. 



It was first observed on cucumbers in 1880 and in 1883. Prof. 

 Forbes of Illinois described it as Aphis ciicumeris and gave an account 

 of its habits upon the plants from which it was named ; but its method 

 of hibernation and early spring history were not traced for many years. 

 Prof. Smith of New Jersey has devoted considerable study to it during 

 the last two or three years, but lacking time for the close and repeated 

 observations required, the investigation was, in 1892, assigned to Mr. 

 Theodore Pergande, one of the entomologists of the Department of 

 Agriculture at Washington. Mr. Pergande's studies have established 

 the fact that the species is identical with the one first described in 

 1854 by Prof. Townsend Glover of the Department as the cotton plant 

 louse (Aphis gossipii), being then only known as a formidable pest of 

 the cotton plant. It was still further identified with what were sup- 

 posed to be two different species attacking the orange tree in Florida, 

 and with a strawberry root louse, discovered by Prof. Clarence Weed, 

 and by him named Aphis forbesi. After thus recitifying its synonomy 

 and bibliography, Mr. Pergande found that it was not by any means 

 confined to the various plants already mentioned, but that it was a very 

 general feeder, occurring on more than 20 of our common weeds, as well 

 as on clover, hops, beans, spinach and other garden plants. This general 

 food habit was a most unwelcome discovery, as it had been hoped that 

 in some stage of its development it.would be found only on one or two 

 plants, on which it might be possible to so reduce its numbers that it 

 would cease to be a formidable pest of melon and cucumber fields. At 

 present there seems to be no ground for such hope and it only remains 

 to fight it, as effectively as possible, when it appears on the vines. It 

 passes the winter on the roots or bases of the stems of herbacous 



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