220 DRY AND MESOPHYTIC FOREST COMMUNITIES 
found, while the digger-wasps and robber-flies of the beach farther back 
come here for flies and other prey. The spotted sandpiper picks 
maggots from the bodies of dead fishes. Mr. I. B. Myers states that 
skunks visit the beach in the night and feed upon the drift. 
2. MIDDLE BEACH ASSOCIATION 
(Stations 57, 58, 710) (Fig. 175) 
The belt within the reach of ordinary waves is usually wet. The 
belt a little higher up, farther from the shore, is characterized by more 
permanent residents. From the often wet margin to the first cotton- 
woods is the middle beach (Fig. 175). 
This middle beach is usually dry in summer but is reached by the 
waves of severe storms and often covered by snow and ice to great 
depths during the winter. It is the final lodging-place for the driftwood 
which stops temporarily farther out. This belt arises in the place of 
the preceding through the former being buried by the depositions of 
sand. In digging into the sand here or elsewhere one usually encounters 
wood and other traces of organic matter. 
a) Subterranean-ground stratum.—In the lower places where the 
ground is usually moist, we find the larvae of Cicindela hirticollis (170) 
which live in straight cylindrical vertical burrows about 6 in. deep. On 
higher ground, where there is the beginning of the incipient dunes, are 
the occasional larvae of the white tiger-beetle (Cicindela lepida) and the 
burrowing spider (Geolycosa piket), which has a burrow similar to the 
tiger-beetles, but larger, and always distinguished by the presence of a 
tubular web at the entrance. Burrowing beneath the sand is the white 
carabid (Geo pinus incrassatus Dej.) and termites or white ants. The latter 
INHABITANTS OF THE MIDDLE BEACH 
Fic. 175.—General view showing the line of cottonwoods and the scattered 
driftwood. 
Fic. 176.—The larva of one of the cabbage butterflies (Pieris protodice Bd.); 
found on sea rocket; much enlarged. 
Fic. 177.—Pupa of the same. 
Fic. 178.—A log on the beach;. favorite habitat of the termites (Termes flavipes). 
Fic. 179.—Termites; a, queen; b, nymph of young female; c, worker; d, soldier; 
twice natural size (after Howard and Marlatt, Bull. 4, Div. Ent., U.S. D. Agr.). 
Fic. 180.—The older cottonwoods of the cottonwood belt. 
Fic. 181.—The adult white tiger-beetle (Cicindela lepida); twice natural size. 
Fic. 182.—The burrow of the larva of the white tiger-beetle. 
