THE CALIFORNIA PEACH BORER. 71 
characteristic habit of the larva in the open field. Whatever the 
surrounding conditions they sought protected places first where they 
could easily penetrate to the tender inner bark. The larve in these 
experiments fed freely after a period of three weeks, when many of 
them were about one-eighth of an inch in length. 
In the open field many larvee enter the trees through old burrows, 
thus at once finding protection in the inner bark. Newly hatched 
larvee have been kept in vials and fed on apricot leaves for several 
weeks, and they probably could have been kept much longer if fresh 
leaves had been properly supplied. 
PERIOD WHEN ENTERING TREES. 
It is seen in Table V, p. 79, that a few moths begin to fly about the 
ist of June, that they are flying in maximum numbers during July 
and August, and that few are flying during September. Table I, 
p. 69, shows that the egg period lasts about two weeks, as oviposition 
begins immediately after the moths emerge. Consequently the larve 
begin to enter the trees during the last half of June, and they enter 
in maximum numbers during July and August and the first half of 
September. The last larvee would be hatching and entering the trees 
during late September or possibly during early October. 
CHARACTER OF INJURY. 
Peach-tree borers usually live below the surface of the ground, but 
under certain conditions and on rare occasions they are to be found 
attacking the trunks and even the large branches. The silver prune 
is subject to attack in this way, and frass and the exuding gum are 
often found on the larger branches several feet above the ground. 
When a tree becomes completely girdled the worms move upward or 
downward into the still-living tissues, and many worms in this way 
may encircle and eat all of the sapwood for from 12 to 16 inches 
above the surface of the ground. This usually occurs during the 
spring, when there is a general upward movement and when the 
worms are preparing to pupate. 
NUMBER OF BROODS AND LENGTH OF LARVAL PERIOD, AS SHOWN BY ““WORMING”’ 
RECORDS. 
The long period in which the larve are entering the trees results 
in a great variation in the size of the larve at any time of the year. 
This has led to the belief that there may be more than a single annual 
brood. Numerous worming records indicate, however, that the 
insect is strictly smgle brooded. It often lives less than a year, 
but seldom longer. Larve that hatch in the early spring or summer 
change to moths early during the following season. Unfavorable 
conditions will delay a few, which will mature in midsummer or fall, 
and in this case their life period is longer than twelve months. Larve 
