34 



Fis. 6. 



The Apple-root Plant Louse (Eriosoma fyri). 



This species is a woolly louse whicbi 

 works under ground and produces upon the 

 roots of the apple tree swellings or excresences 

 (see fig. 6, a) of varying shapes and sizes ;, 

 diseased growths which interfere seriously 

 with the free circulation of the sap, an inter- 

 ference which often results in the death of the 

 parts involved, and sometimes when these in- 

 sects are very numerous their united efforts 

 will occasion the death of the tree. In the 

 more northerly parts of the Northern States 

 this pest is very abundant and with us it is 

 rare to receive a lot of young apple trees either from our own nurserymen or from those 

 of the United States without finding some of them thus affected. 



The mature louse (fig. 6, b) is about the tenth of an inch long including the closed 

 wings of a dull colour with transparent wings and black legs, and with a peculiar downy or 

 frosted look produced by the exudation from its body of a bluish white, cottony matter by 

 which character it can often be readily recognised. When the wings are expanded the 

 insect measures nearly y^ths of an inch, (fig. 6, c). 



As this species, situated as it is under ground requires di£Serent methods of attack from 

 those which infest the leaves of plants and trees we will refer to them here. The only arti- 

 ficial remedy yet suggested for the destruction of this pest is hot water used plentifully so 

 as to scald the roots, or, at least, the larger ones over their entire area. To accomplish this 

 successfully, it will be necessary to carefully remove the earth from about the surface of the 

 roots so as to lay them bare. No danger need be apprehended from using the water scalding 

 hot as the application has often been made without injury. This remedy is not so applicable 

 to large trees as it is to young trees in the nursery row or those lately planted. As a prepar- 

 atory measure, mulching the tree has been recommended, which brings the insects nearer to 

 the surface where they can more readily be reached by the hot water. 



Nature's remedies are, however, in this instance, probably more effectual than any 

 which man can devise. In the first place, these lice are subject to the attacks of a very 

 minute parasitic fly ; and secondly, they are destroyed by the larva of the " Root-louse 

 Syrphus Fl)-," Pipiza radicans, fig. 7 (after Riley). This latter friend is a fat, footless 

 grub, fig. 7a, which lives underground among the lice and devours large numbers of them ; 

 in the fall it changes to a chrysalis, fig. 76, and appears in the perfect form as a fly, fig. 7c, 

 in the following spring. 



^^ 



Fig. 7. 



The Cherry-pl.\nt Louse, Aphis cerasi. 



Probably no species of tree is so regularlj' infested by aphides as the cherr)', and no 

 species included in this large family of pests is more disgusting in appearance than this 

 cherry -plant Mouse, for, while most others are of a more or less lively green colour, 

 this is nearly black. 



These insects begin to appear soon after the leaves have expanded, batching from eggs 

 deposited the previous year. They multiply with amazing rapidity, the young ones hud 



