722 REPORT UXITED STATES GEOLOGICAL SURVEY: 



The question arises whether the cultivation of this weed around po- 

 tato-fields in the East may not be a means of relief from its attacks, 

 though it might breed in larger numbers, if that were possible. 



In Colorado I first noticed the beetle in the vicinity of Denver, where 

 it was not then common, but earlier in the season had ravaged potato-fields 

 out of town. At Golden, July 3, it was observed in abundance on So- 

 lanitm 7'ostraUini, not only the eggs but the larvai in all stages as well as 

 the beetles. I was told by one farmer that he had two rows of potatoes 

 devoured by them earlier in the season. 



It is evident that in Colorado the injury to the potato will always be 

 limited. Five or six miles up Clear Creek Canon it has injured the 

 potato-plants for five or six years, but nowhere above an altitude of 

 about 7,000 feet could I learn that it occurred, and it seems indigenous 

 only to the plains, and the caiions among the foot-hills, l^one were 

 to be seen in Utah. 



Mr. T. Martin Trippe writes me that it destroyed potato-plants early 

 in the season in Howardsville, Southern Colorado. 



Its jowney from the i)lams easi of the Rocicy Mountains to the Atlantic. — 

 The history of the successive invasion of the i^rairies of the Mississippi 

 Valley and of the wooded district of the Middle and Northeastern States, 

 until only the ocean i)roved a sufficient barrier to their advances, is a 

 subject of a good deal of interest to the naturalist, whatever may be 

 thought of the dismay with which eastern farmers have looked upon its 

 arrival. Some years ago it was confidently announced that the Colo- 

 rado beetle would not flourish in the damp, cold climate of ]S"ew Eng- 

 land ; that the summers were so wet that it would die while lying as a 

 pupa under ground. But at the present time of writing, September 15, 

 1870, it is doing perhaps as much damage in the Northeastern States as 

 in the Western, and the newspapers report that it has crossed the At- 

 lantic and eifected a landing in Bremen, Germany, and there is no reason 

 why it should not overrun Europe after successfully withstanding the 

 gre'at differences in climate between the eastern and western regions of 

 the United States. This insect, so indifferent to ordinary climatic dif- 

 ferences, may be compared to a weed which, introduced in a new coun- 

 try, overruns and displaces the native vegetation. Like weeds, the Col- 

 orado potato-beetle, with a number of other widely-destructive insects, 

 may be regarded as prepotent animals. 



Fortunately for the historian of the movements of this insect, the late 

 Mr. B. D. Walsh, at an early date after it began to spread eastward from 

 the plains of Colorado, published in the Practical Entomologist, vol. i, 

 No. 1, October, 1805, an account of its travels. In 1859 it had in its 

 journey eastward reached a point 100 miles west of Omaha, Nebr. It 

 appeared in Kansas and Iowa in ISGl. It entered Southwestern Wis- 

 consin in 1802. In 1804 and 18G5 it crossed the Mississippi Eiver, en- 

 tering Illinois from the eastern borders of North Missouri and from Iowa 

 " upon at least five different points on a line of 200 miles." Thence it 

 has traveled eastward at the- rate of a little over 70 miles a year. In 

 1807 it had appeared in Western Indiana and Southwestern Michigan, 

 and in 1808 had generally overspread Indiana and appeared in Ohio. 

 From the statements of Mr. Eiley, it appears that this insect entered Can- 

 ada in J uly, 1870, and swarmed in 1871 between the Saint Clair and Niag- 

 ara llivers. The same year Dr. Trimble reported its presence in Pennsyl- 

 vania, and in 1871 it also was seen in New York. A southern column 

 advanced eastward into Kentucky, arriving there probably in 1869. In 

 1872 it had reached Lancaster County, Pennsylvania, and Cattaraugus 

 County, New York ; and in 1873, according to Mr. Kiley, it had pushed 



