POTATO INSECTS 143 



Nebraska, the beetles discovered in this new plant a food 

 greatly to their liking. In 1859 the beetles were feeding on 

 potato about one hundred miles west of Omaha in Nebraska. 

 This marks the beginning of the rapid and destructive eastern 

 spread of the species. The Missouri River was crossed about 

 1861 and the Mississippi by 1864. The main line of advance 

 continued around the south shore of Lake Michigan, across 

 Illinois, Indiana and Ohio, down through the natural highway 

 of the lower Great Lakes through Ontario to the Province of 

 Quebec and through Pennsylvania and New York and into 

 New England. The Atlantic Coast was reached in 1874. 

 In the early part of this great migration, the beetles averaged 

 less than fifty miles a year, but after crossing the INlississippi 

 River the yearly advance was considerably greater and the 

 whole distance was covered at an average rate of about eighty- 

 eight miles a year. 



It is now difficult to realize the apprehension with which 

 the farmers viewed the coming of the potato beetle. Spray- 

 ing was then unknown and arsenical poisons had not yet been 

 used for the control of injurious insects. Although the value 

 of paris green for the destruction of this pest was demonstrated 

 in 1869, suitable apparatus for its application was not to be 

 obtained. The first dusting and spraying machines were 

 crude, clumsy and generally inefficient. If one considers the 

 enormous hordes in which the beetles appeared and the com- 

 pleteness with which they defoliated the plants in the newly 

 infested areas, some idea can be gained of the serious situation 

 that confronted the potato-growers of this period. 



In the newly occupied territory the beetles found few of 

 their natural enemies and, therefore, for a time multiplied 

 unchecked. In their eastward advance they moved through 

 a region which was thickly settled, where their food was grown 

 in great abundance and in a climate to which they easily 

 adapted themselves. They were aided in their rapid advance 



