30 BULLETIN 959, U. S. DEPARTMENT OF AGRICULTURE. 
SEASON oF 1918. 
In 1918 in a plat sprayed six times with arsenate of lead and fish- 
oil soap at the usual strengths 77.36 per cent of the fruit was free from 
worms, this being the highest percentage of worm-free fruit obtained 
during the season. In two untreated plats, 8.43 and 24.08 per cent 
of fruit were free from worm infestation. The use of fish-oil soap in 
combination with arsenate of lead gave somewhat variable results. 
The codling-moth trap was of little value as a supplemental control 
measure. Arsenate of lead powder, one-half pound to 50 gallons, was 
about as effective as when used at twice this strength. 
SUGGESTIONS FOR THE CONTROL OF THE CODLING MOTH IN THE 
GRAND VALLEY OF COLORADO. 
The experience of the writers and others who are acquainted with 
Grand Valley conditions indicates that the codling moth presents a 
very difficult problem. As previously stated, there are two full 
broods of larvee per annum and a partial third brood. The moth is 
extremely prolific because of the warm dry climate, and, as a result, 
the apples are exposed to large numbers of newly hatching larve 
practically every day during the development of the fruit. 
The primary object of spraying is to cover the fruit and foliage 
with poison, and when this is properly distributed good protection 
is obtained fora time. Itis, however, quite impossible in commercial 
spraying to coat completely all parts of the fruit, and further, as the 
apple develops in size it gradually outgrows the spray residue. The 
result is, that with numerous larve seeking a place of entrance, somé 
will start feeding where there is no poison, gain entrance, and thus 
produce wormy apples. It is not commercially profitable to spray 
too many times during the season, but a sufficient number of applica- 
tions should be made at such intervals as constantly to provide a pro- 
tective coating of poison on the fruit, paastaul ais) when the larvee 
are hatching in large numbers. 
As a result of the life-history investigations in the Grand Valley 
and other places, it has been found that the development of the cod- 
ling moth from the time of hatching of the first eggs of the season — 
does not as a rule vary to any great extent and that an average can 
be struck which, over a series of years, would usually represent the 
approximate development of the insect with sufficient accuracy for 
spraying purposes. 
Some growers of the Grand Valley have attempted to ascertain 
the time to spray by making observations in the orchard, such as 
inspection of the leaves for eggs and of the fruit for newly entered 
larve. The writers are inclined to believe that this particular method 
as practiced by the fruit grower is unreliable and frequently mislead- 
ing, although regular and systematic inspections over a considerable 
