ARTHROPOD A 169 



when captured, disgorge crayfish and has found garter snakes, 

 Eutaenia sirtalis, in the holes of Cambarus tnonongalensis. The 

 common box turtle catches many crayfish. Many birds, including 

 the eagle, king-fisher, wild ibis and turkey, have been observed with 

 crayfish in their claws; or the remains have been seen at the nests. 



Economic Loss from Crayfish. — The river species do not espe- 

 cially injure human interests except in occasionally capturing a few 

 toads, fish and frogs, but the burrowing species are cited by Ortmann 

 as being very injurious, especially in the lowlands of Pennsylvania, 

 Maryland and West Virginia. They make mud piles which clog 

 harvesting machines, and are considered by the farmers of Maryland 

 as such pests that it is common to throw unslacked lime over the 

 fields in order to kill the unwelcome tenants. West Virginia farmers 

 claim that the crayfish destroys crops of buckwheat, corn and beans 

 by eating the young sprouts. Great damage is done by the bur- 

 rowing species, Cambarus diogenes, in burrowing into dams on ponds 

 and reservoirs, a notable instance being the levees of the Mississippi. 



To destroy crayfish it is customary to throw unslacked lime over 

 the field, or to pour carbon bisulphide into the holes, or to drain the 

 infested area. None of these measures is efficacious, the first two 

 methods being impracticable on account of the difficulty in reaching 

 the bottom of the burrow and the last, simply lowering the water 

 level, only delays matters a little. 



Economic Gain from Crayfish. — With the lobster fishery in a 

 state of decline, it seems as if the crayfish could be profitably sub- 

 stituted for its larger cousin. Crayfish mature in one season and 

 grow to a length of from four to five inches in three years, so that, 

 considering the large number of eggs (100-600) laid by one female, 

 there should be but little difficulty in supplying a large demand for 

 these animals. When we consider that the large Astacus readily 

 adapts itself to the slight difference in environment in the east, we 

 see that the crayfish is a very practicable substitute for the lobster. 

 There should be no difficulty in disposing of the smaller Cambarus^ 

 either as fresh food or canned, as we get the abdomens of shrimps. 



In school and college laboratories, the anatomy of the crayfish 

 has been studied ever since Huxley wrote " The Crayfish." The 

 habits and activities of the young and adult crayfish are of great 

 interest and profit for study. The animal is suited for many kinds 

 of experiments, and the large ganglia and nerve cells are readily 

 removed and are excellent for neurological work. Psychologists 



