266 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
than usual, the midsummer spray will effectively dispose of the first- 
brood worms then hatching, but may not be sufficiently lasting to kill 
all the worms of the summer brood, the late comers of which will be 
hatching 6 to 8 weeks later. If delayed till the second-brood eggs are 
hatching, all the late comers of the first-brood escape, and the grower has 
been obliged to do a good job of guessing just when to spray, or else he 
has had to spray'sufficiently early to insure the destruction of the first- 
brood worms and to use adhesive sprays so copiously that the poison is 
carried on the fruit and leaves until well into September. 
At Marietta, summer-brood moths begin to emerge in late June and 
egg-laying commences in some years about the 4th of July, but usually 
does not reach the climax till early in August. The midsummer spray¬ 
ing should, therefore, be done the first week in July or thereabouts in 
that locality, though in some seasons the moths do not appear numerous¬ 
ly until after July 15. Experience suggests an earlier spray to give best 
control, and the dates used for spraying in Washington County vary 
from July 1 to July 15. The only possible explanation for this necessity 
is that a spray is needed at this time to destroy the late comers of first- 
brood worms, and that the poison will adhere long enough to kill the 
bulk of the summer-brood worms, even though most of them do not 
hatch until sometime in August. The midsummer spray is not so apt to 
be washed from the leaves and fruit by rains as the earlier sprays and, 
therefore, lasts over a, longer period. There is, too, an accumulation of 
poison on the trees from the earlier treatments, making the poison 
cover thicker than it was immediately following the spring applications. 
The midsummer spray is given at Wooster from July 20 to August 1. 
Observation of the results leads us to the conclusion that in the average 
season, July 20 is best. That the blooming was late is not a good cause 
for postponing the spray, but on the contrary seems to be a good reason 
for applying the spray early. In such a season the midsummer brood is 
not delayed so much as the spring brood, and in mid-July, the latter 
part of the spring brood is more damaging than usual. A supplementary 
spray the first week in August may be very desirable in such a y^ear, 
but if this is not applied, apparently the rule should be, ‘‘Apply the 
midsummer spray early and very thoroughly if the season has been 
backward.” 
The progress made in this study has been stated in considerable 
detail in the Monthly Bulletin, Ohio Agricultural Experiment Station 
for May-June, 1923, pp. 73-78. 
