125 
scale. The most efficient remedy is found to be kerosene- 
emulsion in the proportion of about one part of the emulsion to 
fifteen of water. The infested trees should be most thoroughly 
sprayed with this emulsion. Another method, but one which 
is inferior to the emulsion, is to give the tree a thorough 
drenching with a strong solution of whale-oil-soap. In Cali- 
fornia the common treatment is to enclose the tree in a movea- 
ble tent-like covering and to pass hydrocyanic acid gas into the 
tent. As this gas is very poisonous, all the insects on the tree 
are killed. Another remedy used in California is rosin wash. 
Its use may in time become necessary here, but kerosene-emul- 
sion is preferable where efficient. 
Below will be found descriptions of some of the most destruc- 
tive scale-insects in Minnesota. In Fig. 64 are given the dif- 
ferent stages of an insect of this family. 

. Fig. 64,—Scale-insect showing a winged male, a female removed from under the scale. 
‘ the fringe of its caudal segment, a young louse, male and female scales, and egg. 
Original. 
