138 STA.TE HORTICULTURAL SOCIEIY. 



ers appear, and the first generation or two are born, winged forms de- 

 veloping as soon as the plants, which they more especially affect, are 

 sufficiently grown to afford them support. 



Examples of this change of food plant are found in the destructive 

 hop-louse, the eggs and the spring broods of which occur on the plum ; 

 and of the melon-louse which has been traced to the roots of the straw- 

 berry and other low growing perennials. In a few other cases there is 

 evidence that the eggs carelessly dropped to the ground are gathered 

 up by the sharp-eyed ants and preserved in their galleries until spring, 

 and then brought by them to the plants upon which they subsist. This 

 is not benevolence on the part of the ants, but a provident instinct 

 for their own future enjoyment, as it is well known that they are ex- 

 ceedingly fond of so-called " honey dew " which most aphids excrete. 

 Prof. Forbes, of Illinois, who has studied with great perseverance the 

 obscure life-history of the corn-root aphis {Aphis maidis) has found 

 that that the sexed individuals are carried by a species of ant to its 

 nest in the late fall. There the eggs are laid, which are cared' for by 

 the ants throughout the winter, and when hatching takes place, long 

 before the corn has began to grow, the tiny aphids are carried to roots 

 of grass or weeds upon whose juices they make shift to exist until the 

 corn is ready, when they are transferred through underground galleries 

 to their preferred food plant, and are continually watched over and 

 attended to by the ants for the sake of the sweet fluid supplied through 

 their honey tubes. 



The gall-making plant lice form another exceedingly important in- 

 teresting group. Among these we find the Grape Phylloxera, which 

 almost wrecked the wine makers of France and caused the extinction of 

 many choice varieties of grapes in this country. A partial remedy for 

 the evil in Europe was found in the introduction of the more resistant 

 stocks from America, upon which the susceptible varieties could be 

 grafted ; but a recent report brings the discouraging information that 

 in Earopeau soil even the Concord roots in time loose their immunity 

 and succomb to the tiny root-burrowers. It is to be hoped, should this 

 rumor prove true, that Prof. Stedman's aiethod of applying the tobacco 

 remedy, may be found effective against this species as in the case of 

 other root infesting forms. Other species of gall-lice produce the 

 pocket-galls and cockscomb galls on elm and some very singular forms 

 on hickory and other trees. 



Among the insect enemies of plant lice we find fifteen or twenty 

 different species, all of which render important service. One reason 

 why the aphids were so destructive this season is that the floods and 



