THE ROUNDHEADED APPLE-TREE BORER. 5 
LIFE HISTORY. 
To pass through. the four forms or stages of its life cycle this 
insect requires in some cases two years and in others three years. In 
the central part of West Virginia about two-thirds of the individuals 
reach the adult stage the second season after hatching, while the 
other third do not become.adult until the third season from the egg. 
Tt is quite probable that throughout its northern range most or all 
of the individuals require three years to complete the life cycle, while 
farther to the south, where the annual period of feeding is longer, all 
the borers may pass through the same transformation in two years. 
THE EGG AND OVIPOSITION. 
The adult borers issue from the trees Curing late spring and early 
summer, the emergence of the brood 
occupying a period in any given 
locality of from 15 to 20 days. Be- 
tween the southern and northern 
limits of the species’ range the cal- 
endar dates of the beginning and 
ending of the emergence of adults 
probably vary about two months. 
- The beetles occasionally fly by 
night, but are less nocturnal in 
their habits than was formerly sup- 
posed. Emergence from the trees 
takes place by day, as does the lay- 
ing of most, and probably all, of the 
eggs. The males appear two or 
three days in advance of the females 
and usually die first. In a week or Fic. 4.—Heg punctures of roundheaded 
10 days after the females issue egg Bea ecire: hae Seana kage al 
laying begins and is continued for size. (Original.) 
40 or 50 days, a single female de- 
positing normally from 15 to 30 eggs. In preparing a place for 
the egg the female makes use of her jaws to cut a short, curved in- 
cision in the bark (fig. 4); then with her strong, extensile ovipositor 
she forces a side opening from the bottom of the incision (fig. 5), 
at the end of which a single egg is placed. During the period of 
oviposition a female may pass several days without depositing eggs 
and may then lay from 1 to 5 within an hour. Usually at least 2 or 
5 eggs are laid at a time, the operations attending the laying of 
each following close together. The several eggs are as a rule placed 
in one tree. This explains the fact, which has often been noticed, 
