EXPERIMENT STATION WORK WITH INSECTICIDES. 2()3 



therefore become poisoned. In jSIichio^an the first brood does less 

 daniiiiri' than the second, but it must be remembered that the size of 

 the second brood (k'i)ends ahnost entirely on the projjortion of the first 

 brood, which are allowed to reproduce. The a})plication of an arsen- 

 ical durin<j: the first week of August or about the time that the young 

 larvae hatch out reduces the second brood decidedly. AVhere three or 

 more applications seem to be retpiired one may be given soon after the 

 first and another about ten days or two weeks after the first August 

 application. 



In Ohio" active mature larvae of the codling moth were found in 

 orchards from June 30 to October 13, and this indicates the lenjrth 

 of the period during which the fruit is subject to their attacks. In 

 Tmsprayed orchards about 43 per cent of the apple crop showed 

 injury, whereas 01 per cent of the fruit was saved by spraying. 

 According to the experiments at this station, a large number of appli- 

 (;ations of arsenicals is not necessary to control the codling moth. 

 In some instances the first application and in others the late appli- 

 cation aj)peared to be of little value. Since an early application of 

 Bordeaux mixture is required to control apple scab and Paris green 

 may be conveniently mixed with the Bordeaux mixture, it is recom- 

 mended that such a cond)ination be spraj'cd on a]:)ple trees as soon as 

 the petals have fallen, followed at short intervals by two or three 

 other applications, after which one or two applications of arsenate 

 of lead may be made at intervals of two weeks. The effectiveness of 

 the arsenate of lead was not reduced bv being added to Bordeaux 

 mixture. 



The codling moth has long been a serious pest in Oregon.* In this 

 State the larva^ of the codling moth appear to be very abundant late 

 in the season, and this fact must be taken into consideration in tim- 

 ing the applications of insecticides. During a series of si)raying 

 experiments the average of wormy apples on unsprayed trees was 23 

 per cent, while on sprayed trees only 1 per cent was wormy on July 20, 

 but at the time of picking 5 per cent appeared to be infested. The 

 api)lications were made on May 13, June 11, June 2."), and August 11. 

 The results indicate that in most cases the first application is useless, 

 the second and perhaps the third nearly so, while the fourth applica- 

 tion was the one which brought results. These experiments, however, 

 were carried out in a moist climate, and it is stated that in drier and 

 warmer parts of the State the fruit is attacked earlier and an earlier 

 application is theivfore of undoubted value. 



At the Utah Station extensive exi^eriments on means of combating 

 the codling moth have been carried on for several years.*^ In the 

 (>arlier experiments at this station it was found that spraying alone 



o Ohio Sta. Bui. 100. 6 OroRon Sta. Bui. 09. 



" Utah Sta. I'.ul. s7 iiiid other sources. 



