322 STATE HORTICULTURAI^ SOCIETY. 



diluted with nine or ten parts of rain water, the 3 gallons of the formula 

 thus making about 30 gallons to be used in spraying. This diluted emul- 

 sion will probably prove the most effective, although the tobacco has been 

 used with equal success in some instances. Care should be taken in the 

 preparation of either insecticide; many of the reported poor results from 

 the use of insecticides is due to their not being properly prepared and 

 used. 



As it is the young trees that usually suffer, either insecticide can be 

 easily applied with a knapsack sprayer or small force pump. Apply in as 

 fine a spray as possible and drench the trees. In rare cases a second 

 application a few days later may be necessary. The best time to spray is 

 in April or May when the branch forms are the most numerous. 



The root forms will not be reached by this method, hence the relief 

 obtained in this way is only partial. There is on record no experiments 

 in the destruction of this form and we have had no opportunity to make 

 any, but we suggest the use of very liberal quantities of the diluted kero- 

 sene emulsion on the surface of the soil over the roots just before or dur- 

 ing a rain. This suggestion is based on the results of experiments with a 

 species of white grub, the larvse of Allorhina nitida, an insect closely 

 related to the common May beetles of the genus Lachnoster'na. The 

 lawns about the capitol at Washington being badly infested by these white 

 grubs in 1888, afforded an opportunity to try the effects of a dilute kero- 

 sene emulsion applied upon the surface. After applying the emulsion the 

 lawns were thoroughly drenched with water to help to carry the oil into 

 the soil. The result was very satisfactory; after a few days the grubs 

 appeared sick, and a month later no live ones could be found. 



Tf the aphids on the roots of the trees can not be reached by an applica- 

 tion of the emulsion as described above, the trees should be removed at 

 once, burned, and the ground left unoccupied for several months or used 

 for other purposes. The insect could thus be starved out as it is not 

 known to feed upon any other cultivated plants except rarely the plum. 



In the discussion thus far of preventive measures it has been supposed 

 that the pest had already gained a foothold in the nursery or orchard. 

 However, to many peach-growers in the state the pest is as yet unknown, 

 and they will desire to know how they can prevent its getting a foothold 

 among their trees. Growers who raise all their own trees from pits will 

 not be troubled with the pest unless careless neighbors introduce it on 

 stocks purchased in infested regions. 



If it seems necessary to purchase nursery stock elsewhere, and especially 

 in regions known to be infested, it should be quarantined and very 

 thoroughly treated with an insecticide immediately upon its arrival. Dip 

 each tree in either the diluted kerosene emulsion or the tobacco decoction 

 made as described above for use against the branch forms. As the 

 insecticide acts very quickly, the tree need remain in it but two or three 

 minutes. This method it is believed will effectually destroy all aphids 

 that may be on the trees. 



Another method which would doubtless be equally effective is the one 

 used largely in California where the law requires that all trees, plants, 

 cuttings, grafts, buds, seeds, pits, or scions coming into the state shall be 

 disinfected upon arrival. The disinfection is done by fumigating the 

 trees, etc., with hydrocyanic acid gas, a deadly poison. In fumigating, the 

 trees, etc., are placed in an air-tight tent or box, anil for each 100 cubic 



