100 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



FIRST LIST OF THE DERMAPTERA AND ORTHOPTERA OF 

 PLUMMERS ISLAND, MARYLAND, AND VICINITY. 



BY W. L. McAxEE AND A. N. CATJDELL. 



In this paper are summarized the results of collecting of Der- 

 maptera and Orthoptera by members of the Washington Biolo- 

 gists' Field Club and others upon Plummers Island, Maryland, 

 and along the Potomac River from Great Falls to Little Falls. 

 (See PI. XIII.) Like most localities this region yields species 

 verging on the southern border and others on the northern 

 border of their ranges. Such cases always of interest to the stu- 

 dent of geographical distribution, are particularly so here along 

 the boundary between the Piedmont Plateau and the Atlantic 

 Coastal Plain. 1 Species which have a more northerly or highland 

 distribution include: Diapheromera femorata, Spharagetnon bolli, 

 Melanoplus scudderi, M. atlanis, Conocephalus salterns, Atlantic u* 

 americanus, A. davisi, Ceuthophilus gracilipes, Nemobius macu- 

 latus, N. bruneri, and N. confusus. Species more characteristic 

 of the lowland and southerly regions, that occur in our area are: 

 Ischnoptera divisa, I. couloniana, 'Neoconocephalus exiliscanorus, 

 N. caudellianus, N. palustris, Orchelimum laticauda, Falcicula 

 hebardi and Hapithus quadratus. 



The number of species included in the present list by families 

 is: Labiidae, 1; Forficulidae, 1; Blattidae, 7; Mantidae, 1; Phas- 

 midae, 2; Acridiidae, 36; Tettigoniidae, 33; Gryllidae, 24; a total 

 of 105. 2 Of this number 73 species have been taken on Plum- 

 mers Island itself. 



The island has an area of about 12 acres, and considering its 

 topography the number of species of Orthoptera is high. Ap- 

 proximately half of the entire area is wooded lowland and it is 

 flooded usually from 1 to 3 times annually. The higher parts 

 of the island are rocky and the greatest elevation is 75 feet above 

 river level. The southern exposure of the island is warm and 

 often dry, while the northern is shaded, cooler, and usually damp. 

 Otherwise there is little variety of ecologic conditions; there is no 

 stream nor permanent standing water on the island, nor any 

 open grassland. 



The collectors of the material upon which this paper is based 

 are named on subsequent pages in connection with the records of 

 specimens taken. The points at which collecting was done may 

 be located on the accompanying map. In this connection it is 



1 See Rehn and Hebavd, 1916 (2). 



2 The number of species of the same groups in the list for the State of 

 New Jersey (Ann. Rep. N. J. State Museum. 1909) is 154. 



