6 
times diluted kerosene emulsion will give somewhat greater penetra- 
tion and be more effective, although the water alone at the temperature 
named should destroy the lice. This treatment is so simple and inex- 
pensive that it should always be insisted upon by the purchaser if 
there be any indication of the presence of this insect, and stock exhib- 
iting much damage should be refused altogether. 
The fumigation of nursery stock with hydrocyanic-acid gas as for the 
San Jose scale and other scale pests will destroy the woolly aphis. 
After planting, if the trees be kept in vigorous growing condition by 
careful cultivation and, if necessary, proper fertilizing, damage from the 
lice is much less apt to occur, and the principal danger period, namely, 
the first two or three years after planting in the orchard, will pass in 
safety. The value, as a means of protection, of thorough cultivation 
and good care of young orchards can not be too strongly insisted upon. 
Vigorous growing trees have a decided power of resistance or are able 
to sustain with comparatively little damage the presence of the root- 
lice, while ill-cultivated and neglected orchards are especially liable to 
injury. 
The woolly aphis is subject to the attacks of a number of natural 
enemies, including the parasitic chaleis fly, Aphelinus mali Haldemann, 
and the larva of a syrphus fly, Pipiza radicum Walsh and Riley, and 
also the larva and adult of several species of ladybirds, the larve of 
lace-wing flies and spiders, ete. Inthe East a very small brown species 
of ladybird, Scynnus cervicalis Muls., is often present in some numbers, 
and the common nine-spotted ladybird, Coccinella 9-notata, is also an 
active enemy of the woolly aphis. The nine-spotted ladybird has been 
used very successfully in California, on the authority of Mr. Ellwood 
Cooper, to rid trees of root-lice, which was effected by colonizing the 
larvee of the ladybird at the base of the infested tree. All the parasites 
mentioned do much to keep the root-lice in check, and in the case of 
old well-established trees are in most instances a sufficient protection ; 
but in the case of young trees and nursery stock, where the damage 
from the louse is much more rapid and serious, the use of the direct 
remedies outlined should not be neglected; and particularly should the 
nursery treatment be insisted upon. 
C. L..MaRLatTT, 
First Assistant Entomologist. 
Approved: 
JAMES WILSON, 
Secretary of Agriculture. 
WASHINGTON, D. C., March 15, 1897. 
O 
