107 



This is commonly placed within a crevice of the bark, and hatch- 

 ing- in spring- g-ives rise to a new colony. There may be more or 

 less migration back and forth from the groups above ground to 

 those on the roots at almost any time of the summer and fall. 



This insect is universally distributed and extremely common 

 both in orchards and nurseries, becoming- evidently more so to the 

 southward. Being highly injurious to young trees it is a didicult 

 pest to deal with in the nursery trade. It probably cannot be 

 wholly eradicated from an infested nursery, and perhaps can never 

 be completely and permanently kept out of a new plantation. 

 Fortunately trees a few years old, once well established, commonly 

 suffer but little from its presence, and our preventive and remedial 

 measures must consequently be directed to the preservation of 

 young stock. No tree whose roots are visibly injured by the woolly 

 aphis should be allowed to g-o from a nursery, and none in the least 

 infested by it should be sent out until the roots have been freed 

 from it by an insecticide application. 



The simplest method of destruction of the aphis on the roots is 

 dipping for a few seconds in water kept heated to 130^'-150 Fahr. 

 Where heat cannot be conveniently maintained kerosene emulsion, 

 diluted to contain about ten per cent, of kerosene, may be sub- 

 stituted. In the nursery, seedlings or graftings may be protected 

 by using- tobacco dust freely in the trenches in which they are 

 planted, or by sprinkling tobacco dust in a shallow furrow along- 

 each side of the nursery row as closely as possible to the tree, and 

 afterwards covering loosely with earth. Infested trees should not 

 be sent out from the nursery except after fumigation with hydro- 

 cyanic acid g-as or after dipping the roots in hot water or in kero- 

 sene emulsion. Trees with aphis galls or knots on the roots should 

 be thrown out and burned. Those which have been longest in 

 the nursery are commonly the worst infested. Culls kept from 

 year to year are, in most parts of the state, certain to be mere 

 nurseries for the multiplication of these and other destructive 

 insects. In preserving overgrown trees in the hope of making- a 

 cheap sale, the nurseryman usually "saves the penny and loses 

 the pound." 



The Black Peach-Aphis. 

 ( Aphis prunirola. ) 



The Illinois nursery inspectors have not yet reported the occur- 

 rence on peach nursery stock in this state of the black aphis of the 

 peach a species highly injurious and indeed seriously destructive 

 to young nursery trees in some of the eastern states, and prac- 



