450 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
twigs and limbs to attach their cases for hibernation. The case is 
fastened to the bark surface by means of a silken pad or button and 
thereafter the larva remains dormant until the following February or 
March. Hibernating cases measure about 3 to 4 mm. in length, with 
an apical width of about 1.6 mm., and the larvae inside span about 4 
mm. A large percentage of larvae die during the dormant period. 
Activity in spring appears to be governed by climatic conditions 
and by the sap flow of the host plant. On a young Myrobalan tree 
under constant observation in 1912, it was found that the larvae com¬ 
menced feeding about February 18, but all had not become active until 
March 21. In 1909 the commencement of activity on cherry trees 
continued throughout March and into April. The larvae were ob¬ 
served to feed from March 7, at first eating the unopened buds and 
later the young foliage as it pushed forth. In 1910 and 1911 the young 
case-bearers started feeding on plum, apricot and cherry about the 
time when the young leaves began to appear, roughly about March 
20. In 1916, an early season, larvae were working on plum and 
cherry before March, and observations made on March 6 indicated 
that two-thirds had commenced feeding. 
From measurements of larvae collected in March it appears that a 
molt takes place shortly after they recommence feeding in spring 
and that a second occurs soon after. Thus on March 25 and 29, 1912, 
two lots of larvae were collected, one of which had an average head 
width of .53 mm., and the other of .84 mm., the head width of hiber¬ 
nating individuals being in the neighborhood of .38 mm. 
In 1912 the earliest larvae cast their second spring molt before March 
25 and on April 22 it was estimated from collections that about half 
the individuals had cast this molt and that about 2.5 per cent had 
attached their cases preparatory to pupating. A considerable num¬ 
ber of larvae must have been almost as far developed, for on April 27 
it was found that 40 per cent had turned around in their cases. Very 
shortly after this date pupae were found and the latest larvae pupated 
not after May 20. 
The above observations were made on a large series of case-bearers 
confined in a large cage over a Myrobalan plum tree. 
In 1909 collections of pistol-case bearers were made in prune and 
cherry orchards during May, and specimens which had been collected 
in March and caged on apricot were also examined. One such lot 
reared on apricot was examined May 6; the occupants of 71 cases con¬ 
sisted of 4 active larvae, 31 dead or inactive larvae, and 36 pupae. In 
a lot of 105 cases collected from prune May 8 there were on May 10, 
4 living larvae, 7 dead or inactive larvae, 63 pupae, and 31 parasitized 
larvae. In another lot of 47 cases, collected from cherry May 8 and 
