38 
Colorado Experiment Station 
Pig, 31 ,—The European elm scale on the American elm. Adult females as they appear 
in June. Natural size. (After O. E- Essig, “Injurious and Beneficial Insects of Calif.’’ 
Calif. State Com. of Hort.) 
Locust Borer .—A white grub about three-fourths of an inch in 
length when fully grown, that feeds within the trunk and limbs of the 
black locust, destroying many trees. Small white eggs are deposited 
in crevices of the bark during the early fall by the adult insect which is 
a wasp-like beetle about three-fourths of an inch in length. These 
hatch the same fall and the little borers eat into the bark where they 
live over winter. They mature the following July and the beetles 
come out during late summer and early fall. The presence of the borers 
can be detected by the borings that are forced out of the burrows. 
Fig. 32.—Larva of Cottonwood Borer. 
