Proceedings of the Vertebrate Pest Conference

The author describes problems of contamination of foodstuffs in warehouses by commensal rodents, noting that an estimated 95% of such contamination in the U.S. is due to house mice, rather than commensal rats. Other estimates have stated that between 80% and 98% of the food industry’s rodent problem is due to house mice. Pest control operators have often failed to deal with the issue of exterior mice’s ability to access the interior of such storage facility, but rather have concentrated control methods inside the building, rather than searching for the source of the infestation. A study of 7 food warehouses located in Missouri, Kentucky, and South Carolina over a period from 1980 through 1883 revealed the following: exterior house mice were present virtually year-round and were far more numerous than interior mice as shown by trap captures; exterior mice fed on adult insects and insect larvae as well as weed and grass seed; good interior control of mice prevented breeding of interior mice, so nearly all interior mice originated from exterior populations; some mice traveled >200 ft across closely-mowed grass or pavement to reach the warehouse; mice were rarely carried into the warehouse in shipments of palleted foodstuffs. Mouse-proofing specifications are listed, with the intent of showing that exclusion of mice is possible if attention to detail is carried out. PCOs should provide services to retrofit buildings to be mouse-proof, as building managers are seldom able or willing to make this effort. Exclusion should be undertaken in conjunction with use of control measure such as interior and exterior multi-catch traps, bait stations, and glue boards. Details of case histories of successful house mouse control are provided.