i8o 



WET GROUND COMMUNITIES 



The amphipods and sowbugs of the earlier stages are still present. This 

 is the breeding-place of such mosquitoes as the little smoky mosquito 

 (Aedes fuscus) (Fig. 132, p. 178) (145, 99c). 



3. COMMUNITIES OF MARGINS OF BODIES OF WATER 



There is always a narrow area along the margins of bodies of water 

 which is difficult to classify as water or as land. The association of 

 this area is the one with which we now have to deal. 



Along the margins of young ponds and lakes is an area which is 

 characterized by being made up of wet sand or mud which is sub- 

 merged at high water and moist at 

 other times. 



a) A ssociation of the terrigenous mar- 

 gins of large lakes (Fig. 133) (Stations 

 57, 58; Table XXXVIII).— Here we 

 find the springtails the simplest in- 

 sects, the shore bugs (150), Saldidae, 

 especially Salda humilis Say, a large 

 number of tiger-beetles (151) (Cicin- 

 dela hirticollis) (Fig. 134) (C cupras- 

 cens), together with numerous small 

 flies. 



The ground beetle (Bembidium 

 cannula) (Fig. 135) and numerous 

 scavengers are common because the 

 beach is often strewn with dead ani- 

 mals which have floated ashore. The 

 relations of the drift to other com- 

 munities will be discussed in the 

 chapter on dry forests. The spotted 

 sandpiper feeds here, and with the piping plover often breeds not far 

 from the water's edge. Under conditions of rapid recession of the lake 

 such a margin is separated from the wave-action. It is then rapidly 

 transformed into the next association. 



b) Association of the terrigenous margins of ponds and small lakes 

 (Stations 30, 40; Table XXXIX). — This association differs from that of 

 the large lake in that the scavengers are absent and the animals much 

 less active, not moving about so rapidly. Here we find springtails, 

 Saldidae of another species, and the toadbug (Gelastocoris oculatus) (150) 

 (Fig. 136), which is colored like the ground and is found hopping about 



Fig. 136. — The bare pond and river- 

 margin toadbug {Gelastocoris oculatus) ; 

 greatly enlarged (after Lugger). 



