DISPERSAL OF L. DECEMUNEATA. 3 1 



the numbers increased, and the data affords many interesting cases of rapid 

 advance in various directions. 



iSjo. — In the trans- Mississippi region the beetle was numerous, but the 

 injury done was local and due almost entirely to ignorance or to indolence 

 on the part of those farmers who had not yet learned how to deal with the 

 pest. In subsequent years, although the beetle was abundant, few records 

 occur of ' ' great ravages. ' ' 



In Michigan the advance was definitely in a northeasterly direction. The 

 concise reports for the years of the migration of this beetle over the State 

 enable us to trace with precision the spread from county to county. It had 

 covered about half the southern peninsula of Michigan, being numerous in 

 most of the counties and doing considerable damage. The returns of the 

 county agricultural societies report it as present in Barry, Cass, Eaton, 

 Genesee, Hillsdale, Ingham, Lapeer, Shiawassee, and Tuscola Counties (Rep. 

 State Bd. Agr. Mich. , 1870), and in Marion County (Dodge, 1870). In Ohio, 

 Richmond (Rep. State Bd. Agr. Ohio, 1871, p. 542) records the beetle from 

 the garden of J. H. Klippert, in Erie County, and Dodge records it from 

 Van Wert and Mercer Counties. It was also reported by others from Butler, 

 Champaign, Henry, Hocking, Miami, Morgan, Pickaway, Preble, Putnam, 

 and Shelby Counties (Ohio Agr. Rep., 1870). In Missouri it was recorded 

 from the vicinity of Springfield by Holman, and from Greene, Webster, 

 Phelps, Reynolds, Dent, and Texas Counties by Riley (1871). Shimer 

 reports that it was present in the vicinity of St. Paul, Minnesota, and that 

 in Indiana and Illinois it was abundant in some places and not in others. 

 South of the Ohio River it was recorded from Covington, Kentucky (Riley). 



The front of the recorded distribution for this year is materially different 

 from that of 1868 or 1869. Beginning in the north near Bigstone Lake, 

 Minnesota, the line runs eastward to Minneapolis and northeast to the head 

 of Lake Superior, then southeast and by east across two-thirds of the north- 

 ern half of Wisconsin, and then south and southeast to Grand Rapids, 

 Michigan. From Grand Rapids the line runs easterly, aad then northeast- 

 erly to the head of Saginaw Bay, then turns south to Detroit and follows 

 the lake shore to Erie County, Ohio, and then southeasterly to Morgan 

 County. Thence it follows the Ohio River Valley into the south, crosses 

 Missouri to Springfield, and passes west into Kansas, where we have no data 

 of its distribution. The distribution shows for this year a remarkable 

 advance in two directions — ^in Michigan to the northeast, and to a great 

 excess over the usual 70 or 80 miles covered annually ; and in Ohio to the 

 southeast, where the rapidity of advance was so great that the horde along the 

 Ohio River outstripped all others in the race towards the Atlantic Ocean. 

 The rapid advance in Michigan, as also that in Ohio, was due to the fact 

 that the axis of the advance was in the track of well-developed winds, /. e. , 

 the prevailing westerlies. 



