Koford 165 Cynomys ludovicianus June 27, 1955 Nr. Ft. Collins, Colo. had sightings, apparently used. I saw one C.L. in burrow 10'gbs. into ploughed field. About 6 p.m., 1 A. at edge, where formerly many before ploughing. No sure digging by C.L. for seeds of plants, & little evidence feeding on them found (feed on unploughed?). Farthest into ploughed field was 100' in. Ploughing merely a congregation, water worked & smoothed, not a jump of large does, so would not hinder locomotion C.L. Near 2 old mounds at top of slope, 100' yds. from nearest edge field, a little scuffing of soil, possibly by oscar, C.L. visit, but no repair of burnt ours. Drain 4" tall. 1/4 on unploughed bottom, most ground now covered with Salala 10" tall, deep green (eat in pref. grow?). June 28, 1955 Denver, Colo. Talked with Mr. Welch about using herbicides to discourage rodents. He loaned me report of herbicides within relation to Thamnops on Grand Mesa, Clyde Doren of USFS Denver, should also have info on this. For discouraging C.L. from using old burrows on steep slope or other site, Welch recommends spraying burrows with diesel oil (This had been used to discourage Thamnops, ploughing it into soil). Benzene herbicide had also been used, on surface, to discourage rodents. Welch lent me some for trial. This has been under top of ground to discourage rodents, it lasts 300 about 3 mos. atop ground. June 30, 1955. Montrose, Colo. Talked with Ben Crandell, Field & wildlife prob'n & rodent control man, & with Walt Doering, his assistant. In their region there were 3 forms of Cynomys - gerronensis, leucurus, & L. ludovicianus. The last was most difficult to poison & was common now in area