ISO THYSANOPTERA AND ORTHOPTERA. 



pression lying landward of the oldest sand dune, on the north of it. 

 (Pis. IX, Xa.) . Between it and Lake Huron is a strip of'sand ridges 

 roughly parallel to each other, the whole strip averaging perhaps a mile 

 in width (PI. IV b). Rush Lake itself is about two miles long northeast 

 and southwest, by a mile wide, and is comparatively shallow. The 

 bottom is covered in most places with a layer of soft, decaying plant 

 remains, so deep in places that it is difficult to find bottom. Several 

 small islands, some of which seem almost to float on the water, so un- 

 steady are they, are found at various points in the lake. In the 

 water such plants as pickerel weed, water lilies, rushes, Equisetum, 

 and sedges are found. Inland from this lake is clay country under 

 cultivation. Rocks are found only near the shore and were studied 

 by me in only one place near Rush Lake, namely, at Hat Point sev- 

 eral miles to the northeast, on the shore of Lake Huron. Here the 

 rock stands boldly out into the water, forming a blunt promontory 

 with vertical or overhanging walls to a height of some 20 feet above 

 the water. 



This brief description of the region studied will suffice to indicate the 

 character of vegetation which might be expected, and the insect fauna 

 which might depend on the vegetation or directly on the nature of the 

 region itself. 



Six principal objects were kept in view throughout the study: (1) 

 To discover what species existed in a given limited region, including 

 any new species; (2) to devise a scheme of ecology applicable to Thy- 

 sanoptera; (3) to study the habits of the members of the group, with 

 especial reference to their dissemination; (4) to determine their abund- 

 ance ; (5) to study the life cycle of the more abundant species, in so far 

 as it could be done without breeding them; and (6) to consider the 

 economic features of the order. Naturally, some of these received 

 more attention than others. 



In pursuit of the first two objects, I aimed to examine the flowers of 

 ever}' species of plant that bloomed during my sta}^ in the region, and 

 the leaves of. nearly all species. Some species were examined many 

 times. I searched the leaves, I believe, of every species of tree, and the 

 bark of many of them. Practically all the mosses and many of the 

 fungi and lichens were examined, but without success. The various 

 grasses were examined, and the tm-f sifted. All the insect-galls that 

 came to my notice were searched. I estimate that one part or another 

 of over four hundred species of plants were examined. It is not to be 

 supposed, however, that the list of plants infested even approaches 

 completeness; for many unsuccessful examinations of a given flower 

 does not even mai-ce it probable that it is not sometimes infested. For 

 example, the flower of Black-eyed Susan (Eudheckia hirta) was searched 



