15 



if we may judge from the last four years, our breeding-swarms 

 would decrease gradually from one year to another, and if not 

 reinforced from abroad would finally become so few and so scat- 

 tered as to be harmless. 



ANNUAL DEPARTURE OF LOCUSTS. 



Besides the causes already mentioned, still another has been 

 found in the impulse which moves the locust to leave its birth- 

 place on acquiring wings. The considerable numbers that have 

 remained behind each year, have created the impression that none 

 were gone, and that the locust had become a permanent appendage 

 of the state. But a collection of various items for the last three 

 years, together with letters received from the eastern tier of 

 counties in Dakota, shows that considerable numbers have left the 

 state, generally to the northwest in 1874, and in various directions 

 during the past summer. But, with Dogberry, we have been 

 content to "take no note of him, but let him go, and thank God 

 we were rid of a knave." It is only within the last year or two 

 that it has become fully apparent that the final destination of 

 these departing swarms is an important consideration, and one 

 which serves to complicate the locust question more deeply than 

 ever. 



Whether or not it is a general rule that the locusts on acquiring 

 wings seek the direction from which their parents had come in the 

 preceding year, (a rule which the experience of Minnesota fails to 

 substantiate,) it is at least certain that in 1875 "the main direc- 

 tion taken by the insects that rose from the lower Missouri valley 

 country was northwesterly." (Riley's 8th Ann. Report, p. 105.) 

 These swarms were traced by Prof. Riley, moving northerly from 

 the end of May, through June and into July, and passing various 

 points in Dakota, Wyoming and Montana.* 



They passed northward over Bismarck at various times between 

 June 6th and July 15th. (Same report, p, 86.) But a still more 

 definite statement as to the final destination of these northward 

 moving swarms is found in an editorial of the Winnipeg Stand- 



* He adds (page 108) " nor can I learn of any instance where these swarms 

 that left our territory deposited eggs." The different case of our own breed 

 of locusts, layiug eggs within two weeks after the flying commeuces, is re- 

 markable. But I am informed by Captain J S Poland, commanding at 

 Standing Rock, that a swarm from the south alighted near that post, July 

 4th, 1875, and deposited considerable quantities of eggs between the 4th and 

 the 18th of July. 



