MICHIGAN SURVEY, 1905. 



THE ECOLOGICAL RELATIONS OF THE ORTHOPTERA IN THE 

 PORCUPINE MOUNTAINS, MICHIGAN. 



ALBERT PITTS MORSE, RESEARCH ASSISTANT, CARNEGIE INSTITUTION OF 



WASHINGTON. 



1. GENERAL REMARKS. 



The Orthoptera collected by Mr. A. G. Ruthven in the Porcupine Moun- 

 tains represent two families of the Saltatoria and comprise two species of 

 Locustidae and 14 species of Acridiidae. The collection was made' between 

 July 13 and August 12, 1904. Though the list is far from complete, it may 

 be said, in general, that the species obtained are representative elements 

 of the orthopterous fauna of the Canadian and cooler parts of the Transition 

 zones of the central portion of the continent. The commingling of species 

 is especially interesting, and in itself would suffice to indicate, within relatively 

 narrow limits, the locality from whence the collection was derived and the 

 environmental conditions present. 



While data in addition to those of date, locality, and general character 

 of the station are lacking no notes on individual captures or particular 

 species and their relation to the environment in this instance being available 

 I have no doubt that the ecological relations of the species secured are 

 essentially the same as in other quarters of the eastern section of the country. 

 This judgment is confirmed by the careful collecting notes and discrimina- 

 ting observations of Mr. Morgan Hebard in reference to the Orthoptera of 

 the Keweenaw Bay region (Rehn, Entom. News, Sept., Oct., 1904). I 

 have elsewhere (Pub. No. 18, Carnegie Inst. of Wash., p. 15 et seq.) classified 

 the Acridian societies of eastern North America and discussed some of their 

 more salient features. The same classification is followed in the present 

 paper. 



The Acridians secured represent several distinct societies and habitats. 

 These habitats, or complexes of environmental conditions, when viewed 

 from the standpoint of locust biology, may be arranged in three major 

 groups : 



1. Bare rock and soil surfaces of the lake shore, clearing, mountain 

 top, or talus slope, either wet or dry, these are inhabited by campestral 

 geophilous locusts. 



2. Areas clothed with a low vegetal growth of grasses or other herbaceous 

 plants, such as meadows, fields, clearings, etc., likewise varying greatly 

 in moisture content of soil, and often extremely limited in size, these 

 are the haunts of campestral phytophilous locusts. 



3. Thickets of shrubs or stunted undergrowth bordering forest edges 

 and openings, either along the lake shore, about clearings, or on the mountain 

 top, here dwell the sylvan phytophilous species. 



Of the Locustarians collected, one species is a bush-dwelling form, nearly 

 related to the katydid; the other, a shield-backed grasshopper, is a typical 

 thicket-inhabiting species. 



