MONTANA INSECT PESTS, 1947 AND 1948 5 



was more severe than that of the previous year. Their appearance 

 was late because of cold, rainy weather in May and June, which 

 retarded the development and hatch of the eggs. Because of these 

 weather conditions, the hatch was extremely irregular and it 

 extended over a period of approximately three months. One of the 

 most severely infested areas was in the Big Horn, Yellowstone, 

 Treasure, Rosebud, Custer, Powder River, Prairie, Dawson and 

 Richland counties, with heaviest populations occurring along the 

 Yellowstone River and its tributaries. The most heavily infested 

 localized area in the state included eastern Glacier,^ southern 

 Toole, and northern Pondera counties. Small spotted infestations 

 of a more localized nature were also found in sections of the 

 northern and central parts of the state. The dominant species in 

 the northern part of the state were Melanoplus hivittatus, 

 Melanoplus packardii, and Camnula pellucida. The build-up of the 

 latter species was quite pronounced in limited areas within the 

 above region. In the eastern part of the state the dominant species 

 were Melanoplus hivittatus. Melanoplus diffei'entialis, and Melano- 

 plus femur-ruhrum. The 1947 infestation was characterized by the 

 continued build-up of M. hivittatus and M. difjerentialis and an 

 apparent decline of M. mexicanus. which had been the dominant 

 species for many years. The damage caused to crops by these 

 insects was relativelv light considering the heavy populations 

 which were present. This was due largely to the fact that barrow 

 pits, fence rows, rights of ways, and other marginal areas main- 

 tained a heavy succulent growth of weeds which remained green 

 during most of the season. Heavy migrations from these areas 

 were not observed until the harvesting of most crops was well 

 under way. Some damage did occur to new growths of winter 

 wheat in the late fall. 



The weather during the egg laying season was favorable for 

 egg deposition; consequently, heavy egg deposits were found in the 

 infested areas. Western Glacier County had one of the heaviest 

 egg populations that has ever been recorded in the state. In many 

 sections fifty egg pods per square foot was not an uncommon 

 count. 



1948 SEASON 



The grasshopper infestation of 1948 was more severe than any 

 of those occurring during the previous five years. The areas 

 infested were in the same regions as in the previous year but were 

 more extensive. In addition, heavy populations were also present 

 in the Judith Basin area. In general, heavier populations were 

 likewise found in the northern part of the state. The dominant 

 species in the above areas were M. hivittatus, M. difjerentialis, 

 and M. packardii. In the late summer extremely heavy grasshopper 

 populations developed in the range areas in the eastern part of the 



