DISPERSAL Of L. DECEMUNfiATA. 20, 



1866. -During this year the beetle spread slowly eastward, but not as far 

 as in the preceding 3^ears. It seems to have been mainly occupied in com- 

 pletely overrunning the area east of the Mississippi River, which it had 

 already covered, so that in this year it is recorded as injurious to a greater 

 or less extent throughout Illinois and Wisconsin. In the trans-Mississippi 

 region it does not appear to have been more than ordinarily abundant, nor 

 to have done any great amount of damage. In the southern counties of 

 Wisconsin considerable injury was done to the crops (Wisconsin Farmer). 

 In Illinois it was recorded from Bloomington by Walsh (1866$) , from Wood- 

 ford County, and from Athens, Menard County, by Dodge. It was abun- 

 dant in Marshall, Bureau, Champaign, Coles, and Lake Counties (Walsh), 

 and in Winnebago County (Dodge, 1866). It was found near St. Louis, 

 Missouri, but had not been found in the southern part of the State (Walsh). 

 In July it was abundant in Missouri at Hannibal (New York Semi-weekly 

 Tribune, August io, 1866), and at Florisant, in St. Louis County (Cultivator 

 and Country Gentleman, vol. xxviii, p. 16, July 5, 1866). The only eastern 

 advance of any moment recorded was that into western Indiana: "As I 

 predicted, this insect has now spread into .... western Indiana. Accord- 

 ing to Dr. Worthen it occurred in this locality even in 1866." It was also 

 recorded from Hardin County, Kentucky, and from Indiana County, Penn- 

 sylvania (Dodgei, but no specimens were seen, and the records are clearly 

 inaccurate. 



The eastern front of the recorded area of distribution at the end of this 

 year follows the same general course as the boundary for 1865, excepting 

 that it has advanced from 50 to 70 miles. The southward extension does 

 not appear to have been great, but the lack of records indicates only a freedom 

 from injury to crops. Throughout most of the infested area the insect was 

 moderately abundant and destructive, but in the following year there was a 

 marked decrease in the number of individuals and in the consequent ravages. 



186 j. From Indiana the beetle spread eastward into southwestern Mich- 

 igan, where it was reported by Gage (1867) at Dowagiac as having appeared 

 for the first time. It had covered the entire northern and central part of 

 Illinois and northern and western Indiana, and had spread into southwestern 

 Michigan (Rep. Ind. Hort. Soc. , Jan., 1868). In the same year Dodge (1867) 

 records "fearful" ravages in De Kalb and Putnam Counties, Illinois, and 

 its rapid spread and general destructiveness in Brown County, Wisconsin. 

 According to Walsh (1867a), it invaded the southern part of Illinois, being 

 recorded from Union, Marion, and Effingham Counties. Over the infested 

 area as a whole the beetle caused little damage to crops, and, as a result, the 

 records of this year are few and show no great change in the area of distri- 

 bution. The eastern boundary was advanced about 50 miles, excepting on 

 the south in Illinois, where there was a rapid progress to the lower part of 



