4 COLORADO EXPERIMENT STATION. 
arsenical sprays. This season’s work has determined these failures 
to be due to several causes: (i) lack of thoroughness of method; (2) 
lack of proper spraying material, and (3) lack of knowledge of the 
exact life history of the moth. 
The experiments demonstrated that this pest, the most impor¬ 
tant of all to the gruit grower of Colorado, may be cot?rolled by 
arsenical sprays applied properly and at the correct time' 
The number of sprays required to control the moth in an orchard 
will depend principally upon (1) previous infestation of orchard; 
(2) proximity to other infested orchards; (3) efficiency of earlier 
sprays, and (4) variety of fruit. 
To obtain results of greatest practical value to the fruit grower, 
orchard blocks of considerable size were chosen and given treatment 
in the most thoroughgoing and intelligent manner. Records of every 
detail were tabulated, and at the close of the season, in determining 
results, very large numbers of apples were given hand-to-hand inspec¬ 
tion. For example, over 100,000 apples, representing upwards of 600 
bushel boxes, were given a prost critical examination to reveal, as 
nearly as possible, the exact outcome of the experiment. 
Life History Studies —A study of the life history of the moth 
carried through the season showed many things of vital importance 
relating to the proper time to spray. No great variation or change 
of habit of the moth was noted. The time required for the passing 
of each stage of the insect was practically identical with other obser¬ 
vations of the insect in the state. The time or dates of transfor¬ 
mations of the moth were found, however, to be much earlier than 
for the majority of the other fruit sections of Colorado, and some varia¬ 
tion exists between the different portions of the Grand Valley, trans¬ 
formations taking place earlier, as a rule, in the region about Palisade 
than in the country surrounding Grand Junction or Fruita. 
, Parasites —Natural parasites of the insect were studied, one of 
the most interesting being the minute bee, Trichogramma pretiosa , 
laying its eggs and developing within the tiny egg of the codling moth. 
Bands —The use of bands is not discouraged, but they can not 
be depended upon alone to control the moth. If used, the old ones 
which have remained on the tree through the winter should be 
cleaned up by April 1st to prevent larvae from changing to pupae 
and moths making their escape. They should also be gone over at 
least every ten days through the summer until the middle or latter 
part of August, after which there will be little danger of moths emerg¬ 
ing until the following spring. 
Spraying Experiments —As stated, spraying with arsenicals was 
the standard remedy adopted, and the studies were made upon (1) 
Time to spray; (2) Kind of spray, and (3) Way to spray. 
Time to Spray —The time to apply the first spray in the experi¬ 
ment conducted was determined by the condition of the calyx of the 
bloom, and that of the later sprays by careful and systematic obser¬ 
vation for the appearance of the eggs of the moth. 
Close observation of the calyx will determine when it is in an 
