134 AN ECONOMIC ENTOMOLOGY. 



is not unusual for the insects to survive winter in the adult con- 

 dition, without producing a winter egg. One form of the species 

 works deep underground on the fibrous roots ; and this is most 

 difficult to deal with, and often causes the death of the attacked 

 trees. When they appear on the trunk, treatment with either 

 whale-oil soap or kerosene emulsion will be effective, and the 

 underground form can be reached with bisulphide of carbon, or 

 by a liberal use of the tobacco or kainit, as recommended on a 

 previous page. 



We have a number of species that attack our common orchard 

 and farm crops, like the cherry-aphis, Myzns cerasi, the peach- 

 louse, Aphis persicae-niger, the apple-louse. Aphis mali, the 

 hop-louse, wheat-louse, melon-louse, and others of equal reputa- 

 tion. Almost every species requires different treatment, and it 

 is difficult to lay down general rules. Cabbage-lice, which fre- 

 quently do great injury, can be kept down by the prompt removal 

 of all plant remnants left in the field after the heads are taken out 

 and disposed of. On the stumps the insects continue to breed 

 and live during the winter, if not disturbed, either as eggs or 

 adults ; therefore, remove, use up, or destroy them as soon as 

 may be. In pits where cabbage is kept to obtain seed the year 

 following, a great number of lice pass the winter safely, but a free 

 use of bisulphide of carbon will result in their destruction, so that 

 the plants may be set without infestation in spring. An equally 

 important point is keeping down all cruciferous weeds like mus- 

 tard, shepherd' s-purse, and the like, because on these the insect 

 flourishes as well as on cabbage ; therefore, clean culture, not 

 only in the fields but along fences and roads, will pay over and 

 over again. The corn-root louse can best be attacked through 

 its guardian ant, which colonizes the helpless forms upon the 

 roots in spring. Late fall-plowing the corn-fields is indicated 

 here, that the nests of the ants may be destroyed at a season 

 when they are unable to rebuild them. In those sections where 

 fertilizers must be used, the kainit and nitrate of soda, already 

 referred to, will prove effectual. The ' ' apple-louse' ' and ' ' cherry- 

 louse," though different in appearance and habits, have a similar 

 life history, and both pass the winter in the egg state, the eggs 

 being laid on young twigs close to the buds. It is good policy 

 to trim a tree on which there are many eggs pretty thoroughly in 



