DISPERSAL OF I,. DHXEMLINEATA. 27 



ravages, as is evident from Emery's statement "they infest the potato, 

 egg-plant, tomato, and horse nettle." 



The editor of the Wisconsin Farmer (April 13, 1867) states that he found 

 this beetle abundant in Grant County, Wisconsin, as early as 1862, although 

 no specimens were seen from that locality in that year by any entomologist. 

 The publication of this record five years after the date when the insect was 

 first noticed, and then from " I remember" data, might throw some doubt 

 upon its validity were it not true that in the near-by State of Iowa all of the 

 records for the year are of first ravages, so that we are warranted in con- 

 cluding that the State was almost completely overrun with this insect as 

 early as 1861, and in that event its presence in southwestern Wisconsin in 

 1862 is most natural. 



1863. -Additional evidence that this beetle was generally distributed over 

 Iowa is furnished by the record from New Sharon, Nebraska County, where 

 its ravages were so severe "that some were discouraged from planting 

 potatoes " (Fitch, 1863). This bit of evidence from Iowa, indicating exten- 

 sive damage to the potato crop, further confirms the opinion that the beetle 

 was in Iowa in i860 or earlier. In any event, the great numbers and the 

 widespread damage to crops clearly indicate a residence of at least two or 

 three years, and also add greatly to the probability of the correctness of the 

 record from Wisconsin in the year 1862. 



186 j.. In the records of this year we find that the beetles had crossed the 

 Mississippi River into Illinois at several points. In August of the year 

 1864 Walsh received specimens and the following data from the State 

 geologist ( Worthen) : 



It is committing the most destructive ravages on the potato crop in the vicinity of 

 Warsaw, Illinois. I find that the same insect in the same year appeared near New Boston, 

 Illinois. In the autumn I captured two specimens in Rock Island, Illinois, but it has 

 not yet reached a point lying 30 miles east of us in such numbers as to be noticed by 

 farmers. I hear that it has swarmed this year at Mount Carroll, Illinois. It does not 

 appear to have advanced any considerable distance into the State, but it must have 

 crossed the river into Illinois in 1864-65 at five different points. The northernmost lies over 

 200 miles from the southernmost. These records, all settiug forth the damage done, 

 indicate an earlier introduction into Illinois than that given by Walsh, certainly as early 

 as 1S63, so that in the year 1S64 the eastern limits of the beetle were certainly a consid- 

 erable distance east of the Mississippi River. 



On plate 8 the eastern limits of the beetles for this year have been drawn 

 on the basis of these conclusions. 



1865. Abundant reports of the potato beetle in Iowa attest its general 

 distribution in large numbers over the State. So great was the damage 

 done that the potato crop was reduced to half the usual amount. Timble 

 (1865) records placing on the table of the New York Farmers' Club " a large 

 handful of letters, boxes, bottles, and packages from Iowa, all of them con- 



