125 
August 8 one of the larvae had cut off a lateral twig by burrow- 
ing into its base for about 2 mm. and then gnawing a circular 
groove from within. x-Xt this time four of the experimental larvae 
were alive. On August 1 1 a second twig two and a half inches 
from the graft was similarly cut off by the larva within, and on the 
14th still another on the opposite side of the branch, and on the 
1 6th a fourth. The dust holes made by these larvae were from two 
to three inches apart. On the 24th of August the fifth lateral twig 
was girdled five inches down the branch from the graft. On the 
29th and 30th, the sixth and seventh twigs were cut off, these two 
being nearly an inch and a half apart. A larva which was forced 
by grafting to work downward through a twig an eighth of an inch 
in diameter, entered at its base a branch two fifths of an inch thick, 
and continued its excavations just beneath the bark. 
By the 5th of September only two of the larvje remained alive, 
and by the 20th one of them had burrowed a distance of ten and a 
half inches, since its start July 12, — an average of .15 of an inch a 
day. On the 25th of September it was noticed that this larva had 
shortened its burrowed twig by cutting it off from within at the 
place where its last dust vent had been made, and on the 2d of 
October the open end of the burrow was found plugged with wood 
dust, doubtless in preparation for hibernation. On the 14th of May 
one of these twigs was opened and the Obcrca pupa was found with- 
in at the upper end of the burrow. Transferred to a breeding-cage, 
the beetle emerged May 18. The other specimen, still a living larva 
March 13, was used in an experiment with a carnivorous larva of 
Cymatodera halteata, one of the enemies of this insect to be de- 
scribed under another head. 
The Pupa. — Our earliest date for the appearance of the pupa is 
April 16 (1903) and the latest for its occurrence is May 22. On 
the other hand, the earliest date at which we have seen the beetle 
emerge is the loth of May, giving us thus, by inference, a period 
of about three weeks in the pupa state, an estimate borne out by in- 
dividual records from my insectary notes. From a pupa formed 
April 17, for example, the beetle appeared on the 12th of May — a 
period of 25 days; in another instance a pupa formed April 16 
yielded the beetle the 13th of May — 27 days; and in four others the 
pupal period varied from 20 to 29 days. In one case of seemingly 
delayed pupation this period extended only from May 3 to May 19. 
The average of all our recorded observations is 23^ days. 
The dates of the pupal period are especially important, since one 
of the readiest methods of controlling this pest is to clip off, by 
