A HISTORY OF GRASSHOPPER ABUNDANCE SURVEYS AND FORECASTS OF OUTBREAKS IN SASKATCHEWAN 1

Abstract

Saskatchewan had periodic outbreaks of grasshoppers long before the arrival of settlers. With the advent of agriculture these insects threatened the production of cereal and forage crops and necessitated the implementation of extensive control procedures. The effectiveness of control could be enhanced if farmers and government agencies were alerted and informed of the probable intensity and area of outbreak in the coming year. This lead to the initiation of forecasting the expected outbreaks, first, by questioning local persons as to the density, egg laying activities, and damage caused by local grasshopper populations and, secondly, by the inauguration of a special survey system of assessing abundance. Current populations of grasshopper adults or eggs were counted in all arable land areas of the province and rated in four categories of potential outbreak or hazard. The mapping of such ratings in their respective locations resulted in the production of a forecast map which indicated areas of probable light , moderate , severe , or very severe outbreak the following year. In Saskatchewan such maps have been produced annually since 1931 and are reproduced here. They represent the changing scene of grasshopper abundance in the past 36 years and have been accepted by agriculturists as a standard reference to be considered for sound agricultural production in the province.