Among the mice trapped for use in cage trials, gravid females were caught from January through August. Pine mice, intergradations between Pitymys pinetorum scalopsoides and P. pinetorum pinetorum, were found most easily trapped from January through June. The time and energy involved in trapping pine mice for experimental use made laboratory breeding of these mice advantageous. A method for producing captive pine mice was evolved and 19 litters, averaging 2.42 mice per litter, were raised. A number of the captive mice died from fighting and from some apparently infectious disorder. The belligerent nature of the pine mice made changing and rearranging of the cages most difficult. The abnormal condition that killed a number of mice seemed similar to a previously reported disease of pine mice. Of the seed and “grain-like” products tested for palatability; pine mice preferred peanuts, sunflower seed, and chufas; while meadow and deer mice preferred sunflower seed, peanuts and “steam-crushed” oats. The succulent foods tested were preferred by pine and meadow mice in a decreasing order of palatability as follows: apple, pear, sweet potato, white potato, salsify, carrot, turnip, beets, and onion. Some diluents and emulsifying agents, which could be used in applying poisons, were tested for their acceptability to orchard mice. No diluent seemed to enhance, nor materially lessen, the taking of baits. Various poisons were applied in different manners to several acceptable baits and fed to the mice to observe their effect. Sodium fluoracetate (1080) and thallium sulfate proved the most effective, killing 91 and 78 percent of the mice tried respectively. The percentage killed by zinc phosphide, strychnine, arsenic trioxide, and ANTU was much less. All of these poisons, with the exception of zinc phosphide, were eaten rather readily. In most cases, however, a sub-lethal dose was acquired, after which the mice refused to eat further of the particular poison. Poison coated chufas proved most effective in killing pine mice. Both meadow and pine mice were prone to eat the poisoned apple cubes. The difficulty encountered in killing the mice by poisons in cage trials, throws some doubt on poisoning as an effective method of controlling orchard mice.

M.S.