THYSANOPTERA AND ORTHOPTERA. 179 



the definite and accurate working out of the Ufe C3'cles of the various 

 species. This is sure to yield information of considerable biological 

 interest. 



In addition to the acknowledgments made in the general introduction 

 to this paper, I wish to express my thanks to Dr. W. E. Hinds for veri- 

 fying or correcting my identifications of a number of species of the 

 Thysanoptera collected; to Mr. E. P. Van Duzee for the identification 

 of a bug found predaceous on thrips; and to Mr. C. K. Dodge for the 

 determination of most of the plants on which thrips were collected. 

 Assistance pertaining exclusively to the description of new species in 

 my earlier paper (Shull, 1909) was acknowledged in that paper. 



SCOPE OF INVESTIGATIONS. 



All Studies and collections of Thysanoptera were made in Huron 

 County, Michigan, between June 15 and August 27. (See map.) The 

 localities most thoroughly studied were Sand Point, from base to tip; 

 Stony Island, the middle one of three islands which partly enclose Wild 

 Fowl Bay, south of Sand Point; and the region north and east of Rush 

 Lake. Some collections were made in the immediate vicinity of Case- 

 ville; a few habitats were examined near Bayport; and a hasty survey 

 was made of North Island, north of Stony Island. 



A brief description of these regions will be to the point. The shore 

 of Lake Huron was bordered, at nearly every part of the region studied, 

 by smooth beaches and a strip of sand dunes, of variable width. It 

 thus happened that the great majority of localities studied were of a 

 sandy nature. (Pis. I, II, III.) Sand Point, which projects about 

 four miles westward into the bay, north of Wild Fowl Bay, was nearly 

 all sand and comparatively well wooded. Two or three small lakes or 

 ponds were found on it, and several interior places were c^uite wet when 

 work was begun in June, but were rapidly drying. At the base of the 

 point was a treeless area of several hundred acres called the "prairie", 

 which was said to have been ciuite marshy in the spring, but was nearly 

 dry during the summer. (PI. AT.) Inland from this "prairie" was clay 

 farming country. At Caseville the sandy strip was very narrow, the 

 cla}' country reaching almost to the lake. On Stony Island, with an 

 area of some 900 acres, the sand was least in evidence of any of the 

 localities studied. Good sand beaches were almost wanting, rocks 

 were scattered rather profusely over the bottom in shallow water, and 

 on the west side of the island there was an outcropping of bed rock. 

 (PI. XIV.) In the interior were several small ponds (PI. VIII b) and 

 dry marshes; on the east the island was bordered by low wet areas 

 (PI. V). 

 ■ Rush Lake, four or five miles to the east of Caseville, occupies a de- 



