12 



one-fourth of their growth before winter. At this time, they are enclosed 

 in brown leathery cigar-shaped cases and feed upon the soft substance 

 of the leaves ; the winter cases are curved and broader. The other species 

 which forms pistol-shaped cases is not so common in Ontario, but may 

 occasionally prove troublesome ; its habits are similar to those o# the 

 Cigar Case-bearer. Both may be kept in check by the sprayings already 

 referred to. 



Fig. 18. Apple tree Pistol Case-bearer. 



Apple Plant-Lice (Aphis), Figs. 19-22. There are at least three 

 species of Plant-lice affecting the Apple in this Province, namely, the 

 Apple Aphis (A. mali), the Rosy Apple Aphis (A. malifolice), and the 

 Woolly Aphis (Schizoneura lanigera). The first two infest the tender 

 new growth of the branches and the leaves, which they injure very much 

 by sucking the juices and thus checking the development of the shoots 

 and causing the leaves to shrivel. They are minute pear-shaped creatures, 

 soft-bodied, green, pink or blackish in color, destitute of wings for the 

 most part until the autumn, when the winged forms appear. The third 

 species, the Woolly Aphis, attacks the roots of the apple, producing knots 

 and swellings and causing much injury, and also is to be found in col- 

 onies on limbs and branches, especially where there is any exudation of 

 sap from cuts or wounds in the bark. They are covered with a delicate 

 white material which looks like cotton-wool and gives the special name 

 to the insect. As these minute creatures live entirely by suction, it is 

 impossible to poison their food, but they may be got rid of by substances 

 which close up their breathing pores and suffocate them. Kerosene emul- 

 sion applied as soon as they are observed in the spring, and repeated 

 whenever the colonies reappear, is an effective remedy. Tobacco decoc- 

 tion and Whale-oil Soap may also be used with good results, and are ro 

 be preferred where only a few trees require to be treated. The under- 

 ground form is very difficult to get at, but may be destroyed with bisul- 

 phide of carbon poured into holes made in the ground above the infested 

 roots and then covered up. 



