MONTANA INSECT PESTS, 1947 AND 1948 7 



dominant species in this area for several years. Some flights of 

 M. mexicanus were observed in the eastern part of the state and 

 a heavy flight was reported to have moved into Northern Montana. 

 As in 1947, the grasshopper damage to crops was relatively light in 

 1948 because of the succulent marginal growth. In some cases, even 

 though heavy populations of M. hivittatus and M. packardii were 

 observed in grain fields, the actual damage to these fields was 

 slight. Some damage did occur, however, due to leaf and head 

 feeding. The above species do not cut the heads and cause the 

 severe destruction that occurs when M. mexicanus are present. 



Large amounts of organic insecticides were used in grass- 

 hopper control — the most common of which were Toxaphene and 

 Chlordane. These materials gave excellent control when used as 

 sprays or dusts in succulent foliage. They serve to replace baits 

 which are generally ineffective under these conditions. 



In scattered localized areas, hopper populations were greatly 

 reduced by scarcophagid flies. Fungus and bacterial disease were 

 also responsible for slight reductions in grasshopper populations 

 in alfalfa and mustard fields. Unfortunately, these parasites did 

 not occur over large enough areas to be of great significance. 



THE OUTLOOK FOR 1949 



The 1948 fall surveys of adult and egg populations indicate 

 that the grasshopper infestation for the coming season may be one 

 of the most severe since the 1939-40 outbreak. As was previously 

 pointed out, all of the infested areas have increased in size and 

 heavy populations have developed in many new areas. This is 

 especially true in the northern and central part of the state. The 

 heavy build-up of M. mexicanus and the apparent spread of this 

 species from the eastern part of the state as well as from other 

 areas, indicates that it may soon be the dominant species in Mon- 

 tana. If this infestation does occur, increased crop losses are 

 imminent. 



OTHER IMPORTANT PESTS 



WIREWORMS (Elateridae) 



During the last biennium the damage from wireworm activi- 

 ties has increased considerably. Their presence was confined to 

 limited areas spotted throughout Montana. In the eastern two- 

 thirds of the state most of the wireworm damage occurred in small 

 grains. In the western third, damage commonly occurred in pota- 

 toes and sugar beets. During the last season, wireworm damage to- 

 sugar beets was considerably heavier than in previous years. 



GARDEN SLUGS (Agriolimax agrestis) 

 During the 1948 season, garden slugs were a major pest in the 



