6 MONTANA EXPERIMENT STATION BULLETIN 366 



properly carry out the duties required of the office. 



The appropriation provided by the last session of the Mon- 

 tana Legislature made possible the employment of two full-time 

 assistants, Mr. O. B. Hitchcock, who has been working on Mor- 

 mon cricket control activities, and Mr. H. R. Willis, for the 

 grasshopper campaign. It also made possible the hiring of tem- 

 porary help, the puchase of a limited amount of equipment and 

 the rental of district warehouses for the storage of materials 

 purchased by the Federal Government. In addition a small 

 amount of investigation into the effect of Mormon crickets on 

 the range, and an extension of the annual grasshopper survey 

 was carried on. 



Further research is necessary because, while it is true that 

 a measure of control has been developed for the great majority 

 of harmful insects, there are few if any for which these methods 

 cannot be refined in effectiveness and cost or new ones dis- 

 covered. One line of research of extreme importance, but not 

 yet receiving its proportionate share of attention, is that of fore- 

 casting increases in insect populations. Certain insects seem to 

 do best in dry weather, others in wet. For the majority of them, 

 however, the factors governing their increase or decrease are 

 not known. In 1936 there were serious outbreaks of the false 

 chinch bug (Nysius ericae Schil.) and the forest tent caterpillar 

 (Malacosoma disstria Hbn.) . The next year they were absent in 

 any numbers and the lined sphinx moth (Celerio lineata Fab.) 

 was abundant. In 1932 the Say's grain bug (Chlorochroa sayi 

 Stal.) , which had been observed in small numbers in the State 

 since 1901, appeared in large numbers and caused considerable 

 injury to wheat in the Triangle Area north of Great Falls. It 

 has remained in injurious numbers up to the present time. When 

 its period of high populations will end is not known. This past 

 summer the common field cricket (Gryllus assimilis Fabr.) has 

 been extraordinarily abundant in many areas in the northern 

 tier of counties, and in some places farther south. It is not 

 known whether or not it will increase to injurious numbers next 

 season. Until information is available concerning the factors 

 governing these increases in insect populations, the actual con- 

 trol work will be greatly handicapped. 



