8 MONTANA EXPERIMENT STATION Bui. 139 



such numbers as to completely defoliate the trees. One defoliation 

 presents a fruit crop and a very few successive defoliations will 

 kill the trees. Careful estimates show that this insect did $25,000 

 worth of damage in the Bitter Root Valley during" the year 1920. 

 Inspectors of the Board of Horticulture and representatives from 

 this office have found the leaf-roller to be widely prevalent through- 

 out pretty much all of the Bitter Root Valley and indications are 

 that unless determined steps for its control are taken it will continue 

 to multiply and extend its ' distribution until the whole valley is 

 involved, in which case very extensive damage may result. In com- 

 pany with representatives of the Board of Horticulture, the State 

 Entomologist held public meetings of fruit growers in the early 

 spring of 1920 and advised the use of miscible oils to be applied 

 before the buds had started. This is the standard remedy for this 

 insect and lias been moderately successful in other states where it 

 has been used. The time was so short that it was not possible to 

 conduct any preliminary experiments for the purpose of getting 

 more exact information to govern us, and very unfortunately the oil 

 that was used did not control the outbreak and serious damage 

 resulted. 



A representative from this office made a careful study of the 

 entire situation during the summer and arranged to conduct experi- 

 ments after the eggs had been laid. These experiments consisted of 

 removing whole limbs on which had been laid large numbers of 

 egg clusters, spraying them with different miscible oils in various 

 strengths, then leaving them in a greenhouse under observation at 

 the college, and later comparing the numbers that had hatched in 

 each experiment. 



Parallel with this experiment trees in the orchard were sprayed 

 and limbs were removed and carried to the greenhouse at Bozeman 

 where observations were made. Indications at the present time are 

 that we shall be successful in finding among the tests a satisfactory 

 remedy to be used in the orchards of the Bitter Root Valley during 

 the spring .it" 1921. It is our intention to give definite attention to 

 the control of this insect and bring it under control if a means can 

 be fotind. 



THE ALFALFA WEEVIL SITUATION 



The alfalfa weevil is a very destructive pest of the alfalfa plant 

 which was first found in this country in the vicinity of Salt Lake 



