CON"TROL, OF CODLING MOTH IN COLORADO. 31 



portion of the orchard will sometimes give information of value. As 

 a rule, however, fruit growers have neither the time nor patience to 

 undertake a careful orchard survey. On account of seasonal varia- 

 tions, calendar dates for making applications can not be depended 

 upon, but a schedule based on certain intervals following the dropping 

 of the blossom petals will usually result in timely spraying. 



In formulating the control of the codling moth it is very important 

 that the approximate time of the fir.st hatching of each brood of larvre 

 and the relative number of worms that are developing from time to 

 time be known. Complete and reliable data of this nature were 

 obtained in the foregoing life-history studies, and with these data 

 at hand it is believed that the most effective time for making the 

 spray applications can be established. 



The spray schedules that follow are based on the life-history studies 

 of 1915 and 1916 and take into consideration the time when each 

 brood begins to hatch, the time when the larvae are hatching in large 

 numbers, as well as the time when hatching occurs in maximum 

 numbers. Three sets of schedules, I, II, and III, all starting from the 

 time 90 per cent of the petals have dropped, are presented in Table 21, 

 by reference to which it will be seen that schedule I calls for five 

 applications and is intended for orchards having a relatively light 

 infestation and for varieties on which the codling moth is not difficult 

 to control; schedule II, six applications, for a medium infestation and 

 for varieties on wiiich the codling moth is moderately difficult to 

 control; schedule III, seven applications, for a heavy infestation and 

 for varieties on vrhich the codling moth is most difficult to control. 



The codling moth is normally abundant in the Grand A^alley, and 

 apples such as the Ben Davis, Schackelford, and other susceptible 

 varieties will usually require schedule III, or seven treatments, 

 especially if from previous neglect or other cause the infestation is 

 very heavy; whereas, under similar conditions of infestation, varieties 

 hke thcWinesap, on which tlie codling moth is more readily controlled, 

 will require a smaller number of applications, as in schedules I or II. 

 The degree of infestation varies somewhat from year to year and in 

 the difl'erent fruit districts, and, as previously stated, the control of 

 this insect varies with the different varieties. For these reasons, no 

 one schedule will meet the demands of all the growers, and it will be 

 necessary for each individual to forecast in advance what his conditions 

 are likely to be and spray accordingly. 



