2,2 DISTRIBUTION AND DISPERSION OF LEPTINOTARSA. 



i8ji. Over the whole of the infested area the beetle appears to have been 

 more numerous this year than during the two or three preceding. Riley 

 (1871) gives the following account of an occurrence in the Lake Superior 

 region : 



Juno Hurlburt, who has been engaged in surveying and prospecting in that part of the 

 country, . . . found them in immense quantities in a potato field belonging to some 

 Indians on the Menomonee River, yet this potato patch was on a clearing of about 20 

 acres, and to his certain knowledge there could not have been another potato patch 

 within 150 miles. 



Riley attributes this occurrence to their being carried down stream to that 

 point. Dodge records the beetle as injurious in Columbia, Ozaukee. Outa- 

 gamie, Portage, Richland, Dane, Fond du Dae, Green Dake, Iowa, Juneau, 

 Kenosha, St. Croix, and Sheboygan Counties, Wisconsin ; in Fillmore, 

 Carver, Houston. Kandiyohi, Meeker, and Ramsey Counties, Minnesota ; in 

 Barry, Bay, Cass, Kent, Kalamazoo, Monroe, Newaygo, Ottawa, and Van 

 Buren Counties, Michigan, and in several counties of Ohio, Indiana, Illinois, 

 and Iowa. It was also found in Livingston, Manistee, Saginaw, Shiawassee 

 (crop a failure), and Tuscola Counties, Michigan (Rep. Sta. Bd. Agr. , 187 1), 

 while south of the lakes it had spread from eastern Ohio into western Penn- 

 sylvania and New York. In Missouri the southward spread was slight. ' ' It 

 has not yet reached the southern counties" (Riley 1. 



The chief event in the history of this year's spread is the invasion of Canada. 

 The beetle had been abundant in eastern Michigan and Ohio, especiall}' along 

 the shore of Lake Erie, but before the end of the year it had crossed the lake 

 and overrun a large portion of the Province of Ontario. Riley (1 871) describes 

 its methods of crossing the lake thus : "In the spring the Detroit River was 

 swarming with the beetles and they were crossing Lake Erie on ships, chips, 

 staves, and any floating object. ' ' The following agricultural societies reported 

 its presence in their section of the country : Both well, Brandt (S.), Elgin (E.), 

 Essex, Huron, Kent, Lamberton, Middlesex (E.), Oxford (N.), Simcoe (N.), 

 Wentworth (N.), and York (N. and W.). The insect did but little damage 

 in this year (Ann. Rep. Comm. Agr. and Pub. Work, Prov. of Ont., on Agr. 

 and Arts, 187 1). They were most numerous on the western frontier between 

 Sarnia, Lamberton County, on the north, and Amherstburg, Essex County, 

 on the south, and inland from 20 to 40 miles (Sanders and Reed). They 

 were found along the north shore of Lake Erie in small numbers as far east 

 as Toronto, York County. 



The front of the area occupied this year is bounded by a line which, 

 beginning at the western end of Lake Superior, runs southeasterly across the 

 middle of Michigan to Saginaw 7 Bay ; thence along the shore of Lake Huron 

 to Port Huron, across the St. Clair River to Sarnia, in Lamberton County, 

 through Stratford, in Perth County, to Toronto, in York County ; thence 



