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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
noted on August 8, 17 days earlier than in 1916. In other words, cod¬ 
ling moth activities started off one and a half months behind that of 
1915 and by the time eggs of the second generation were deposited were 
just two days behind. The first brood of 1917 started off 20 days be¬ 
hind that of 1916 and by the time eggs of the second generation were 
deposited it had gained 17 days. 
Prevailing warm weather continued throughout August, September 
and October during which time the second brood of insects was very 
active in 1917. Hatching of the eggs reached its height during the 
middle and latter part of August but continued until the fruit was har¬ 
vested. Eggs on the fruit in the boxes were found while checking up 
experiments as late as October 16. This continued activity made it 
advisable for our station to recommend an extra moth spray, sugges¬ 
tions for the application of which were given out for September 5. 
At this point the question might be asked whether it was not a par¬ 
tial third brood of insects which caused the deposition of eggs found 
late in October. A series of the earliest matured larvse of the second 
generation were caged and their activities watched during the remainder 
of the season; in not a single instance did pupation occur. A study of 
this character has been conducted during some of the other seasons but 
up to the present time no indications of the occurrence of a partial 
third generation has been observed at Hood River. 
As a general practice in the past in most of the sections of the North¬ 
west, spraying for the control of the second generation of worms has 
been supposed to be necessary between the 25th of July and the first 
of August. This was the belief of local orchardists at the time the 
writer began the study of this insect at Hood River. In 1914 the study 
checked up nicely with these suppositions; the 27th of July being the 
time recommended for spraying. In 1915 the spray was applied most 
effectively August 12; in 1916—where it was necessary—August 28; 
and in 1917 on August 12. In two years out of the four the recom¬ 
mended date for applying the summer application of arsenate of lead 
was the same; with the extremes there was more than a month’s differ¬ 
ence. Those of you not entirely familiar with codling moth control 
might ask the question: What material difference would it make if the 
spray was applied even 10 or 12 days before egg hatching? The an¬ 
swer would be in terms of obtainable results in ordinary seasons of 
infestation, the difference between complete control as against one half 
or even less control. In other words, an application of spray cannot be 
completely effective during a period, not to exceed 20 days at this time 
of the year, owing to the rapid growth of the fruit and its necessary 
partial uncovering. If a spray is applied 10 days in advance of the 
brood hatch, one half of its complete effectiveness is forfeited at the 
