108 



tically certain to appear sootier or later in Illinois. In fact it may 

 be already present in our peach orchards, since no especial atten- 

 tion has lately been g-iven to peach insects in this state. 



As it passes the winter upon the roots of infested trees it is 

 extremely likely to be transmitted in the nursery trade, and it has 

 been frequently reported to have been introduced into new districts 

 by this means. Sling-erland mentions, for example, a New York 

 orchardist who broug-ht the black peach-aphis into his orchard by 

 replacing- trees which had died by younj? trees from an infested 

 Delaware nursery. As far back as 1892 it was very common 

 throughout the great peach-growing districts of New Jersey, Dela- 

 ware, Maryland, and Virginia, ranking in destructiveness next to 

 the disease known as peach-yellows. Nearly one hundred thou- 

 sand trees were killed in a single nursery in one of these states 

 within two or three weeks in 1890, while many other large nur- 

 series were badly affected and some entirely destroyed. 



The presence of this peach aphis upon the roots is indicated, 

 according- to Sling-erland, by a stunting or dwarfing- of the young- 

 trees such that those three or four years old have sometimes made 

 scarcely any growth. The leaves are lig-ht g-reen or yellowish, 

 more or less rolled at the margin, and often spotted with red and 

 purple from the effects of fungi. If the aphis becomes very abun- 

 dant the tree dies outrig-ht, and another set in its place takes the 

 same fatal course. Certain parts of the orchard may thus come 



Fig. 2. The Black Peach-Aphis, Fig. 3. The Black Peach-Aphis, 



wingless female. winged female. 



to be regarded as "dead spots,"' owing to the continuance of the 

 black aphis in the earth. The principal injury is done under- 

 g-round, but some times the insect will appear in great numbers 

 upon the twig's and leaves, causing- the usual curling of the foliag-e 

 and dwarfing- of the terminal growth. 



It occurs in two forms, one wingless (Fig-, 2) and the other pro- 

 vided with large transparent wings (Fig. 3). The wingless insect is 



