April, ’24] 
gossard: codling moth control 
265 
SHOULD THE MIDSUMMER APPLE SPRAY BE TIMED FOR 
THE SECOND BROOD ONLY OF CODLING WORM? 
By H. A. Gossard 
Abstract 
Studies of the life history of the codling moth, Carpocapsa pomonella , have been 
made, partially or fairly complete, at Marietta in southern Ohio, at Wooster in the 
north central section and at Gypsum in the northwestern section. Records of the 
dates when the sprays are commonly applied have also been kept through a series of 
years. The stages of development of the moth at the dates of spraying are shown by 
the life history chart. The tentative conclusion is reached that when the season is 
late the summer spray should be earlier than usual instead of later and that a later 
second summer spray is desirable in such a year. 
It is quite generally assumed by orchardists and entomologists that 
the July spray given to apples in Ohio and nearby states should be 
specially timed for the second brood of worms and if timed to work 
most havoc with this brood, it is likewise assumed that the results will be 
more acceptable than if the spray is given earlier or later than this 
pivotal date. 
After a good many attempts to render this spray most effective by 
timing it according to data secured by rearing the moths in cages and 
from held observations, moth traps on the tree trunks, egg-laying records, 
etc., we raise the question if the best date can be determined by this 
method; or if we must supplement such data by experience data and 
settle upon a time that has given maximum results through a long period 
of years. Results are so frequently disappointing from the spray after 
all possible care has been taken to put it on after the moths have com¬ 
menced to emerge and just w T hen egg-laying has commenced, that it 
seems worth while to discover why a spray, so timed, sometimes gives a 
much more wormy harvest than sprays put on neighboring orchards at 
an earlier time, chosen on the basis of average experience. 
Studying the life-history of Carpocapsa pomonella in relation to the 
dates when the midsummer spray is commonly applied in Ohio, as 
shown by records extending over several years, it appears that the ex¬ 
planation may lie in the overlapping of the broods of codling worm. 
As shown by the life-history chart the eggs of the spring brood are still 
hatching when the moths of the second brood commence to emerge and 
there is from 1 to 3 weeks overlapping of the larvae of the spring and 
summer broods. This overlapping comes in the month of July, six 
weeks or more after the last treatment for codling worm is given, follow¬ 
ing bloom, if the usual schedule is followed. If given a week earlier 
