428 Agricultukal Experiment Station, Ithaca, N. Y. 



work frequently appears when there is nothing to indicate the 

 existence of an insect as its cause. A stunting or dwarfing of the 

 young trees is one of the most marked symptoms of the presence 

 of the pest. Sometimes three or four-year old trees are but little 

 larger than when first set. The foliage of such trees presents a 

 yellowish-green sickly appearance. Karely a tree after languish- 

 ing a year or two recovers and makes a good tree. Under favor- 

 able conditions the insect may appear in great numbers on the 

 tree above gixmnd and its growth be nipped while yet in the bud ; 

 the growing shoots dry up and the young tree soon dies. 



Its past history. — This insect has been known to the peach 

 growers of the Atlantic States for more than a quarter of a cen- 

 tury. From 1860 to 1875 it was particularly destructive to ]Mary- 

 land. In 1874 it is first recorded as appearing above ground in 

 desti'uctive numbers. WTiile investigating the Peach Yellows in 

 1887, ]Mp. E. F. Smith came across the insects upon the roots of the 

 trees; and as the YeUows had by some been attributed to this 

 aphis, Mr. Smith made many observations on the pest from which 

 we get most of our knowledge of its life history and habits. The 

 severe outbreak of 1890 has already been noted. Two or three 

 years ago the pest wais carried into the Michigan peach district 

 on nureery stock from the east. It seems not to have gained a 

 foothold among the California orchards as yet; the Board of Hor- 

 ticulture of that State is fully alive to the importance of the pest, 

 and it is on the alert to prevent its introduction. 



Its classification. — This insect is one of the true bugs belonging 

 to the same family — the Aphididae — as the Grape Phylloxera, 

 the Grain Aphis, the Hop Louse, and many other well known 

 plant-lice pests. Scientifically the insect is known as Aphis per- 

 sicae niger — the Latinized foi-m of the common name, Black Peach 

 Aphis. This name was given it in 1890, by Mr. E. F. Smith, who 

 after comparing it with descriptions of allied known species 

 became convinced that the species was new and so described it. 

 Mr. Smith believes that the insect is a native species, as he found 

 it common on the roots and branches of the wild pliun, Prunus 

 chicasa, thus indicating that this may be its original food plant. 



