No. 3.] DAWSON — THE LOCUST INVASION. 123 



River Valley before their wings were fully developed. In 1874, 

 winged swarms again came in from the west, leaving an abun- 

 dant deposit of eggs over all parts of the province. 



The records thus include, for this area, a period of fifty-eight 

 years, and during that time locusts may be stated to have 

 appeared either on the wing from abroad, or directly from the egg, 

 in numbers sufficient to attract attention, in fifteen seasons, but 

 caused wide-spread and serious destruction of crops in ten years 

 only. The record shows an exceptional and alarming increase 

 in the frequency of invasion of late years, an increase which has 

 also been noticed in the Western States, and which though no 

 doubt partly due to the fact that larger tracts have come under 

 cultivation and consequent observation, apparently leaves a 

 balance in favour of some real cause of increase ; and this it 

 should be the object of every one interested in the matter, to 

 ascertain if possible. 



In 1874, in British America, it would seem that no locusts 

 were produced from the egg east of the 103rd meridian, and per- 

 haps not east of the 104th, though southwards, in Dakota, some 

 are said to have hatched near Minnie Wakan Lake, long. 99°, 

 and the young insects also appeared in several localities on the 

 Missouri River, near long. 101° lat. 47°. From various places 

 included between the 104th and 111th meridians, and the 49th 

 and 53rd parallels of latitude, the insects are known to have been 

 produced in large numbers ; and from the outcoming direction 

 of swarms, and other facts, it may be safely concluded that 

 eggs were hatched in many places over this great uninhabited 

 tract. The young locusts do not seem to cover uninterruptedly 

 any great area, but to occur in extensive patches here and there, 

 where flights of the preceding season have rested. Nor do the 

 separate swarms arrive at maturity at exactly the same time, 

 though a sudden change in the weather, and more especially of 

 the wind, may cause a nearly simultaneous departure of broods 

 from a large tract. In 1874, in the area in question, movement 

 appears to have begun late in June, and continued during July ; 

 the direction of flight where it has been recorded, lying between 

 east and south. On July 12th, I observed swarms ready for 

 flight on the high plains near White Mud River (long. 107° 35' 

 lat. 49°.) The day was hot and calm, and though many of the 

 insects were on the wing at all altitudes, they were following no 

 determinate direction, but sailing in circles and crossing each 



