a1 Entomology Division, Mauritius Ministry of Agriculture, Natural Resources and the Environment, Reduit, Mauritius
The distribution and seasonal abundance of Stomoxys nigra nigra Macq. and S. calcitrans (L.) in Mauritius was determined by field surveys in 1973–74. S. nigra, the species of major importance, is most common throughout the wetter, higher elevations where it becomes a major pest of cattle. S. calcitrans occurs throughout the island to a much lesser extent. Coastal areas with less than 60 inches of rain are generally free of damaging infestations of both species. Seasonal infestation levels were determined by making counts of flies feeding on animals and of flies on resting surfaces. Populations of up to 200 S. nigra per animal were highest during the warm, wet, sugar-cane cropping season but declined to generally non-damaging levels during the cool season. S. calcitrans increased up to 145 flies/animal during the cool, drier season and virtually disappeared during the wet season. S. nigra accounted for up to 98% of the total Stomoxys infestation with S. calcitrans making up 62 % of the total at one study site during the study.
Sugar-cane debris in fields was found to be the primary breeding source for 5. nigra, whereas decaying manure and organic matter provided the source for S. calcitrans. Generation-to-generation increases were usually below five-fold for both species. Both species exhibit two feeding peaks throughout the day at temperatures of 14°C or above.
(Received February 10 1975)
(Revised March 03 1976)
* Entomologist, Food and Agriculture Organization, United Nations Development Program. Current address: USDA, ARS, VTERL, P.O. Drawer GE, College Station, Texas 77840, U.S.A