220 



STATE BOARD OF AGRICULTURE 



Grand Rapids, Michigan, about when such an appearance might be 

 expected in Michigan, should the aphis appear at all in numbers. 



No corrections were made for elevation above sea level, the computa- 



looseh'. I will say that this computation was 



tion being made rather 



Fig. 1 — Healthy pea plant compared with one injured by pea-louse 



based on the work of Dr. A. D. Hopkins of the Bureau of Entomology, 

 whose investigations on the progress of the seasons from the south to 

 the north is our standard source of information. 



It w^ould appear from these computations that we might expect a 

 similar development at the latitude of Grand Rapids and Kent City 



