Insect Notes for 1920 9 



fall of 1919 was very favorable for egg laying, and eggs hatched in 

 enormous numbers in June, 1920. A campaign for grasshopper control 

 was put on in the infested counties and much poison bait was used 

 by the farmers. This fact coupled with the wet June, prevented grass- 

 hopper development in Minnesota. Hence only in a few local areas 

 was much damage done. 



The dry fall of 1920 was again very favorable for grasshopper 

 egg laying, so the grower must be alive to danger from these pests in 

 1921. It is hoped that the experience of the last season will help 

 materially in spreading the gospel of control measures. 



Cutworms and army worms. — The year 1920 was notable for the 

 absence of the common varieties of cutworms which work in fields 

 and gardens in the spring. Altho there was a widespread and serious 

 outbreak of the Variegated cutworm, in 1919. this species was present 

 only in very small numbers and practically no complaints were re- 

 ceived. 



There was also an outbreak of the army worm in 1919, which 

 covered a large part of the state. This species was also reported in 

 1920, altho from an entirely different part of the state. In 1919 the 

 area of greatest abundance covered the northwestern part of the state 

 nearly as far south as the Minnesota River, and another infested 

 region extended from near Duluth to the southern boundary along 

 the Mississippi River. In 1920 the southwestern part of the state, 

 south of the Minnesota River, was attacked, with the centers of heavi- 

 est infestation in Yellow Medicine and Lyon counties. Reports of 

 damage w'ere received from practically all the counties west of Man- 

 kato and south of the Minnesota River. 



Reports came in about ten days later than in 1919, following a 

 cool, wet spring which retarded the growth of the larvae. An interest- 

 ing feature of the season's work was the failure of the worm to form 

 true marching armies. A visit was made to the infested regions the 

 first week of August, and it was found that in no case had the armies 

 marched more than a few hundred feet. The individual armies were 

 small, but there were sometimes three or four distinct armies, originat- 

 ing from as many centers of infestation in a single field. 



The apparent cause of this failure to march was to be found in 

 the weather conditions at the time of egg laying. The latter part of 

 June and the first week of July were very wet, and many favorable 

 places for egg laying could be found in any field. This accounted for 

 the smallness of the armies and their quite uniform distribution over 

 the section. A belt consisting of the northern parts of Cottonwood 



