18 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
Complaints of both fall and spring canker-worms are frequently 
received by the Bureau of Entomology. Correspondents often report 
that they are unable to protect their trees by the use of arsenicals, and 
the opinion has at times been expressed that these insects can not be 
destroyed by arsenical sprays. While it has often been stated in the 
literature on canker-worms that they are more resistant to poisons 
than many other species of insects, yet there is no doubt that they 
may be readily killed by thorough use of poisons. In most cases the 
poor results from spraying are evidently due to failure to make thor- 
ough applications of the spray, the large size of the trees and the 
unfamiliarity of the orchardist with spraying operations often con- 
tributing to this end. 
In the present brief article the life history and habits of the spring 
canker-worm are given, together with results of practical work in its 
control. The hfe history and habits of the fall canker-worm prac- 
tically parallel those of the spring species, except that the great 
majority of the moths of the former species emerge and oviposit in 
the fall. The operations of spraying and plowing herein discussed 
will be equally effective in its control. 
LIFE HISTORY AND HABITS. 
There is but one generation of canker-worms each year. After 
obtaining their growth on the trees in the spring, the larvee enter the 
soil to a depth of from 2 to 5 inches, and after making an earthen 
cell transform to pupe (see Pl. III, fig. 3), in which condition they 
remain until the following spring. Early in the spring, or even 
during warm spells in winter, the pupe transform to moths, which 
make their escape from the soil and go to the trees. The males are 
winged, as shown in Plate III, figure 5, but the females are destitute 
of wings, as illustrated in Plate III, figure 4. In ovipositing the 
females climb the trees and place their eggs in irregular masses under 
loose bark scales, in cracks in the bark, in crotches of limbs, etc., as 
shown in Plate III, figure 1, which illustrates an egg mass which was 
placed on the underside of a bark scale. The number of eggs in an 
individual mass varies greatly. Females taken presumably before 
oviposition had begun deposited eggs in confinement, the number to a 
mass varying from 17 to 119, with an average for 12 masses of 47. 
An individual egg is elongate-elliptical in outline, somewhat 
resembling a hen’s egg in miniature. The average dimensions of ten 
recently deposited eggs were found to be 0.69 by 0.42 mm. When 
first deposited the surface is shining, pearly white, but in the course of 
a few hours the egg takes on a yellowish-green color, in certain lights 
showing a golden, greenish, or purplish iridescence. As the embryo 
approaches maturity it becomes very evident and lies curled around 
just within the shell, its cephalic and caudal ends together, the egg- 
