Dr. G. R. La Rue suggested the use of dung in place of dead fish, as he 

 believed that these snails might be coprophagous and become infected by 

 eating trcmatode eggs voided in feces. Accordingly, small cloth bags of 

 feces were planted in the mud and found to be equally as effective as the 

 dead fish, and more conveniently handled. Dung of dog, cat, ferret, 

 muskrat, and chicken was tried. After a few preliminary experiments, 

 chicken dung was used exclusively. It was dried before use, which elim- 

 inated objectionable odors and permitted it to be packaged in quantity 

 and stored to be used as needed. Dried dung was as effective as fresh. 



To make a snail trap, a quantity of dried chicken dung is placed in 

 the center of a cloth 9 inches square, the corners twisted together and tied 

 with heavy cotton twine, leaving free enough to tie to a stake. Double 

 thickness of washed cheesecloth is ideal; heavier cloth resists rotting for a 

 longer time but also retards the passage of the fecal extract. The twine 

 should be capable of resisting rotting in water, since these packets remain 

 effective until their contents are gone. The packets are tied to stakes and 

 placed in suitable habitats for Campeloma. 



Choice of location is important. In streams these snails frequent shal- 

 low, mucky situations and plantings should be made here; gravel areas in 

 deep water should be avoided. When properly planted, the packet should 

 be half- buried with the stake projecting above the water level far enough 

 to be easily recognized. In areas frequented by many people, the plantings 

 should be inconspicuous to prevent possible interference. This can easily 

 be accomplished by using dark-colored cloth and stakes made of tree 

 branches; in summer, willow is especially suitable because the leaves remain 

 green and willow looks natural along the banks of streams. 



The trap remains effective for approximately 6 weeks, but to get the 

 best results the location should be changed every 10 days or 2 weeks. The 

 snails are collected by removing the trap and screening the mud from an 

 area about 15 inches square around it by means of a screened scoop or 

 spinach strainer. 



It was suspected that in streams the current might carry fecal extract 

 which the snails followed to its source at the trap. This idea was tested by 

 planting marked snails at various distances, 2 to 15 feet, upstream, as far as 

 20 feet downstream, and 10 feet across the stream from a trap. In collec- 

 tions made at weekly intervals for 5 weeks, 28 of the 67 snails (41.7 per- 

 cent) planted upstream, 24 of the 86 (26.7 percent) planted downstream, 

 and 2 of the 9 (22.2 percent) planted across the stream were taken at the 

 trap. Practically the same number of snails moved to the trap from 15 feet 

 upstream and 20 feet downstream as from 2 feet up and downstream. My 

 data indicate that the snails move at random. Once arrived at the trap, 

 however, they tend to stay as long as the food supply lasts. 



In lakes the traps proved ineffective. Experiments to determine the 

 reason for this have not been carried out. All the lakes tried had bottoms 

 of sand underlaid by muck which perhaps provides sufficient food for 



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