Excessive losses experienced by nesting ducks on the Crescent Lake National Wildlife Refuge were detd., in 1938, to be attributable to bullsnakes (Pituophis sayi). As a remedial measure a funnel type of trap with drift fence was developed and operated. During 4 yrs. (1939-1942, inclusive) 1,729 bullsnakes were removed through trapping. A lowering of nest losses from 35% in 1938 to 18.5% in 1942 is attributed largely to the results of this trapping. As by-products of this trapping, other valued information was obtained regarding bullsnakes, many of which were tatooed and released for subsequent recovery. Facts on drift, growth, sex ratios, reaction to heat, and food habits were accumulated. More than 1,000 stomachs (about 3/4 empty) were examined. The 2 dominant food items were meadow mice and duck eggs.