TEMPERATURE AND POPULATION-DENSITY EFFECTS ON FEEDING-ACTIVITY OF STOMOXYS-CALCITRANS (DIPTERA, MUSCIDAE) ON CATTLE

The relationship of population density and temperature to feeding acti vity of stable flies, Stomoxys calcitrans (L.), on cattle was studied by placing cattle in constant temperature chambers with controlled fly density and. temperature. The number of flies per front leg declined within hours after release but increased with fly density and temperat ure. The time flies spent on the host during a 5.5-h exposure period r anged from <2.5 min at temperature <16 degrees C to >34 min when tempe rature was >20 degrees C. Estimates of the temperature threshold for f light ranged from 10.7 to 20.1 degrees C and were influenced by densit y and time after release. Nearly 45% of the feeding flies were on the front legs, and this proportion was unaffected by density, temperature , and time after release. In the field, the number of flies per forele g also was influenced by density and temperature. Estimated flight thr eshold was 10.7 degrees C, low enough to allow flight during 41-95% of the daylight hours from May through October in southern Alberta.