FLOOD-PLAIN FOREST COMMUNITIES 199 



taken the larvae of the viceroy butterfly (163) and the larvae of the 

 cecropia moth (Samia cecropia Linn.). Doubtless forest-edge birds 

 nest here also. 



The belt which succeeds the willow is commonly found farther from 

 the water and has not been so much studied. It is commonly made up 

 of larger willows, river maples, young elms, young ashes, and small 

 hawthorns. These are usually much tangled with weeds such as nettles, 

 and masses of flood trash and vines. General collecting in such a situ- 

 ation along Thorn Creek (August) secured for us the large green stink- 

 bug (Nezara hilaris), the spiny assassin-bug (Acholla multispinosa), and 

 the broad- winged fulgorid (Ampliscepsa bivittata). On the maples are 

 frequently larvae of Symmerista (Fig. 151). On a small hawthorn were 

 a number of larvae of the handmaid moth (Datana). At this stage the 

 trees and shrubs become the nesting-places of the yellow warbler and 

 American goldfinch, which are probably our most characteristic early 

 flood-plain birds. 



In the wet ground of the flood-plain, especially in any small depres- 

 sions made by overflows, the crayfish (Cambarus diogenes) is the charac- 

 teristic resident. Under driftwood and on the plants of the water 

 margin is the slug (Agriolimax campestris) , and often also the snails 

 (Succinea retusa and avara). 



Such situations are also the chief haunts of the beaver, which cuts 

 away the saplings to make its dams. The otter (Lutra canadensis) is 

 particularly fond of stream margins. It feeds upon crayfishes, fishes, 

 frogs, etc. It has particular powers of traveling long distances and a 

 curious habit of sliding down mudbanks and snowbanks for sport (142). 

 In winter it progresses on ice by repeatedly running a distance and then 

 sliding as far as the momentum will carry the body. The nest is nearly 

 always in the stream bank, with the entrance below water. The skunk, 

 the mink, and the raccoon are also fond of the stream-margin thicket, the 

 latter picking up fish or crayfish if they can be had at night. This animal 

 is said to wet its food before devouring it; hence the "wachbar" of the 

 Germans. The skunk likewise devours almost anything that is to be 

 had at the water's edge. 



d) Flood- plain forest association (Station 68; Table XLVIII). As 

 times passes the river cuts lower, the forest develops, and we have 

 a dense forest of elm, hawthorn, ash, and basswood, with sometimes 

 walnut and butternut, these being partially displaced on the higher 

 ground by the oaks. This we may regard as the typical flood-plain 

 forest. 



