The blackflies in the autonomic region of South Tyrol-Trentino and their veterinary medical importance

The blackfly fauna of South Tyrol-Trentino consists of twenty-four species, of which Simulium argyreatum, S. colombaschense, S. ornatum, S. reptans, S . variegatum and S. voilense were responsible for loss of animals in the ye ars 1996 - 1998. In 1996 eighty-one cattle, in 1997 twenty cattle and in 19 98 twenty-five cattle, thirteen calves, one horse and one pig died because of blackfly bites. S, colombaschense was found in Italy for the first time in the river Etsch. The deaths occurred between the middle of April and the end of August after a rapid rise in air temperature in 700 m up to 1,800 m sea level. The typical clinical picture consisted of petechial, partly fus ing haemorrhages of the skin, particularly at udder and scrotum, oedema at the brisket, hypogastrium and area of the vulva, as well as accelerated bre athing, increased pulse rate, diminished activity of the rumen, and circula tion insufficiency. In 1999 precautions were taken by monitoring the turnout of cattle and thei r housing when blackfly activity increased. Mortality was not observed in 1 999. Reasons for the sporadically increased abundance of blackflies are dis cussed.