102 FIRST ANNUAL REPORT OF 



Mr. Walsh showed that originally its exclusive home was in the Uocky 

 Mountains, where it had been known to exist for at least forty-five 

 years feeding upon a wild species of potato peculiar to that region 

 ( Solarium rostratum, Dunal); that when civilization marched up to 

 the Rocky Mountains, and potatoes began to be grown in that region, 

 it gradually acquired the habit of feeding upon the cultivated potato; 

 that in 185!), spreading eastward from potato patch to potato patch, it 

 had reached a point one hundred miles to the west of Omaha city, in 

 Nebraska; that in 1861, it invaded Iowa, gradually, in the next three 

 or four years, spreading eastward over that State; that in 1864 and 

 18(55, it crossed the Mississippi, invading Illinois on the western bor- 

 ders of that State, from the eastern borders of North Missouri and 

 Iowa, upon at least five different points on a line of two hundred 

 miles; and that in all probability it would in future years tl travel on- 

 wards to the Atlantic, establishing a permanent colony wherever it 

 goes, and pushing eastward at the rate of about fifty miles a year."' 

 (Practical Entomologist, Vol. I, No. 1.) A remarkable peculiarity in 

 the eastern progress of tnis insect was subsequently pointed out by 

 the same writer, in 186t3, namely, that "in marching through Illinois 

 in many separate columns, just as Sherman marched to the sea, the 

 southern columns of the grand army lagged far behind the northern 

 columns." (Ibid, II, p. 14.) 



Now, let us see how far the predictions above,, have been verified 

 By the autumn of 1866, the Colorado Potato-beetle, which appears to 

 have invaded the south-west corner of Wisconsin at as early a date as 

 1862 (Ibid, II, p. 101), had already occupied and possessed a large parfc 

 oft he cultivated or southern parts of that State; and in Illinois if we draw 

 a straight line to connect Chicago with St. Louis, nearly all- the region 

 that lies to the north-west of that line was overrun by it. It subse- 

 quently invaded parts of South Illinois, occurring in Union, Marion, 

 and Effingham conn-ties, in 1868; and already in 1867 it had passed 

 through the eastern borders- of North and Central Illinois into West- 

 ern Indiana, and the south-west corner of Michigan; and finally, in 

 1868 it made its appearance in many different places in Indiana, and 

 as the following communication from a Cincinnati correspondent of 

 the Ohio Farmer, under date of July, 1S68, will show, it has even 

 spiead into Ohio. 



" About three years ago when in your office at Cleveland, yon 

 presented me with samples of this devastating insect,, the first I had 

 seen; they have been preserved in the collection of one of the best 

 entomologists of Ohio. You had received the beetles from some cor- 

 respondent in Iowa, where it was then ravaging the crops and where 

 it continues to be very destructive. We soon learned that the insects 

 were progressing eastward at the computed rate of about thirty miles 

 a year, and we began to calculate the time when we might expect its 

 appearance in Ohio — which, we did not anticipate for some years.. 



