TWENTY-EIGHTH REPORT OF THE STATE ENTOMOLOGIST 5 



mood to fly, and did infest parts of Toole, Pondera, Teton, Wheat- 

 land, Golden Valley, Musselshell, Rosebud, Petroleum, and possibly 

 Valley, which were not so heavily infested during the summer. This 

 lack of mass flight for considerable distance was probably due to 

 the weather conditions during the flight period, and to the great 

 reduction in populations as a result of the intensive control pro- 

 gram. 



It is interesting to note that the migration of 1938 invaded an 

 area in which grasshoppers were on the decline and that there were, 

 considering the State as a whole, fewer of them in 1940 than in 1939. 

 They were apparently able to hold up their populations primarily 

 on the strength of the immense numbers present even though condi- 

 tions were not the best for their increase. 



MAJOR INSECT CONTROL PROBLEMS 



Grasshopper Control in 1939 



The unusual conditions prevailing during 1939 in the badly in- 

 fested area in eastern Montana were (1) high infestations on deplet- 

 ed range, (2) almost a pure infestation of Melanoplus mexicanus, 

 (3) a hatch almost two weeks earlier than was expected, (4) an ex- 

 tremely even hatch, (5) uniformly excellent kills with poison bait, 

 and (6) high local interest in the control campaign. While there 

 was a high incidence of egg predation by bee fly and blister beetle 

 larvae, the large numbers of eggs which remained produced exces- 

 sive populations. In irrigated valleys the two-striped grasshopper 

 (Melanoplus bivittatus) appeared locally in some numbers, and 

 along fence rows and roadsides in Judith Basin and Fergus counties 

 they were moderately abundant. There was very little hatch until 

 May 5th, when a spontaneous hatch occurred in parts of Prairie, 

 Custer, Rosebud, Dawson, McCone, and Richland counties. In sur- 

 rounding areas the appearance of nymphs was delayed a little. The 

 evenness of the hatch was demonstrated by counts made in the area 

 the fourth week in May. At that time 68.9 per cent were in the 

 second instar, 23.3 per cent in the first, and 7.7 per cent in the third, 

 with over 90 per cent of the eggs hatched. A great deal of -rain 

 fell for about three weeks beginning May 19th. The counties east 

 of a line drawn through Carbon and Phillips counties had received 

 100 per cent of their normal rainfall for the April to August period 

 by the last of July, and most of Valley, Daniels, Sheridan, and 

 Roosevelt counties had received 125 per cent of the normal. Baiting 

 operations were stopped, but conditions were such that some peri- 

 odic feeding kept most of the 'hoppers alive. Mild migration move- 

 ments were first noted on the 25th and 26th of June, and they con- 

 tinued until the latter part of July. 



In 1937 the big-headed grasshopper (Aulocara elliotti) was sec- 

 ond only to M. mexicanus as the dominant species in the State. In 



