6 Farmers’ Bulletin 1270. 
is shortened to an average of about 2 weeks. The incubation period of the egg 
during the relatively cool spring weather will frequently extend over 2 weeks, 
although the average period is usually about 8 or 9 days. Later in the 
seuson this average is reduced to 6 or 7 days, and there are records in 
the Bureau of Entomology of an incubation period as low as 4 days. The 
feeding period of the larva is also prolonged in the spring, sometimes almost 
to 2 months, with an average of about 38 to 4 weeks, while during the summer 
the larve usually complete 
their feeding within about 
3 weeks. 
The control of the codling 
moth is largely effected by 
spraying with a poison, such 
as arsenate of lead, de- 
scribed on page 83. The 
number of spray applica- 
tions required to secure sat- 
isfactory results will vary 
with the locality, the num- 
ber of generations, and the 
relative abundance of the 
insect. In the northern latitudes good control is frequently obtained with from 
one to three applications, whereas in districts having longer seasons, or wherever 
the moth is naturally abundant, as in the semiarid valleys of the West, it is 
often necessary to spray from five to seven times. ; 
The time of the application is very important, and although no detinite 
schedule that will meet satisfactorily the conditions obtaining in all parts of 
the country can be given here, the following suggestions will be of value. 
The first application should be made in every 
orchard just after the blossoms have dropped 
(fig. 180) and this application should be com- 
pleted before the calyx lobes close. (fig. 181). 
In order to cover large orchards in time it is 
oftem necessary to commence spraying when 
only 85 to 90 per cent of the blossoms have 
fallen, but care should be taken not to spray 
when the trees are in bloom and attractive to 
bees. The object of this application is to de- 
posit in the calyx cup a quantity of poison 
sufficient to kill all the larve that endeavor 
later to enter the apple through the calyx end. 
The calyx cup is open at the time the blossoms 
drop, but is closed about a week later, after 
Which it will be too late to force the poison into 
the cavity. No subsequent spray can be of much value in preventing calyx 
worms, hence the great importance of this application. 
The first larvie or worms begin to hatch in most sections about 3 to 4+ weeks 
after the blossoms have fallen, although in some districts, and particularly if 
the weather is warm, a few worms will commence to hatch in from 2 to 3 
weeks following the fall of the bloom. The second spray should therefore be 
«“pplied in from 2 to 4 weeks after the first in order to coat the leaves and 
young fruit with poison just previous to the hatching of the early worms. In 
fruit districts where the insect is difficult to control, one or two additional 
Tic, 4.—Codling moth larva and pupa within cocoons 
beneath bark of apple tree. Enlarged. 
ic. 5.—Codling moth resting 
on apple leaf. Fnlarged. 
