ENTOMOLOGY 391 



To facilitate the wetting of the roots and the extermination of the 

 aphides, as much of the surface soil as possible should be first 

 removed. 



By a hot-water bath slightly infested stock can be easily freed 

 of the aphides at the time of its removal from the nursery rows. 

 The soil should be dislodged and the roots pruned, and in batches 

 of a dozen or so the roots and lower portion of the trunks should be 

 immersed for a few seconds in water kept at a temperature of 130 

 to 150 F. A strong soap solution similarly heated or a fifteen 

 times diluted kerosene emulsion will give somewhat greater penetra- 

 tion and be more effective, although the water alone at the tempera- 

 ture named should destroy the aphides. 



Badly infested nursery stock should be destroyed, since it would 

 be worth little even with the aphides removed. 



Tobacco Dust. Some very successful experiments conducted 

 by Prof. J. M. Stedman demonstrated the very satisfactory protec- 

 tive, as well as remedial value of finely ground tobacco dust against 

 the woolly aphis. The desirability of excluding the a'phis altogether 

 from nursery stock is at once apparent, and this Professor Stedman 

 shows to be possible by placing tobacco dust freely in the trenches 

 in which the seedlings or grafts are planted and in the orchard ex- 

 cavations for young trees. Nursery stock may be continuously pro- 

 tected by laying each spring a line of the dust in a small furrow 

 on either side of the row and as close as possible to the tree, and 

 covering loosely with earth. For large trees, both for protection 

 and the destruction of existing aphides, from 2 to 5 pounds of the 

 dust should be distributed from the base outward to a distance of 2 

 feet, first removing the surface soil to a depth of from 4 to 6 inches. 

 The tobacco kills the aphides by leaching through the soil, and acts 

 for a year or so as a bar to reinfestation. The dust is a waste pro- 

 duct of tobacco factories, costs about 1 cent per pound, and possesses 

 the additional value of being worth fully its cost as a fertilizer. 



Kerosene Emulsion and Resin Wash. Either the kerosene- 

 and-soap emulsion or the resin wash, the former diluted fifteen times 

 and the latter at the strength of the winter mixture, are used to 

 saturate the soil about the affected plants and either left to be carried 

 down by the action of rains or washed down to greater depths by 

 subsequent waterings. 



For the grape phylloxera or the root-aphis of the peach or 

 apple, make excavations 2 or 3 feet in diameter and 6 inches deep 

 about the base of the plant and pour in 5 gallons of the wash. If 

 not a rainy season, a few hours later wash down with 5 gallons of 

 water and repeat with a like amount the day following. It is better, 

 however, to make this treatment in the spring, when the more fre- 

 quent rains will take the place of the waterings. 



For root-maggots enough of the wash is put at the base of the 

 plant to wet the soil to a depth of 1 to 2 inches, preferably followed 

 after an hour with a like amount of water. For white grubs in 

 strawberry beds or in lawns the surface should bo wetted with kero- 

 sene emulsion to a depth of 2 or 3 in-ches, following with copious 



