The southward spread of buffalo fly (Haematobia irritans exigua) in eastern Australia and its survival through a severe winter.

The southward spread of buffalo fly (Haematobia irritans exigua) in coastal eastern Australia from Bororen, Queensland in 1974 to Coffs Harbour, New South Wales in 1982 is documented. Surveys after a cold, dry winter in 1982 recorded overwintering sites and subsequent spread of flies in southern Queensland and northern New South Wales. Buffalo fly overwintered at several places in the Maryborough-Bauple districts and further north. Overwintering also occurred in the Currumbin Valley-Mudgeeraba area on the Queensland-New South Wales border. Other infestations detected early in the season and believed to have arisen from local overwintering populations were observed at Kin Kin, Mount Tamborine and Flinders Peak. By May 1983 flies had recolonised much of coastal south eastern Queensland, and as far south as Ballina and west to the Richmond Range in New South Wales. Implications of these findings for control are discussed.

The seasonal tick populations on traditional and commercial cattle grazed at four altitudes in Natal.

The number of ticks collected over a period of one year from cattle at 4 altitude levels in Natal, Republic of South Africa, are plotted against meteorological and seasonal data. Collections were made from both traditional and commercial cattle at each altitude. Most of the economically important tick species show clear seasonal patterns of activity. This suggests that strategic dipping could be used as a means of control.

The potential geographical distribution of the Old World screw-worm fly, Chrysomya bezziana.

The potential geographical distribution and relative abundance of the Old World screw-worm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) as determined by climate, was assessed using CLIMEX, a computer program for matching climates. CLIMEX describes the relative growth and persistence of animal populations in relation to climate. The observed global distribution of C.bezziana was compared with the potential distribution predicted by CLIMEX. The differences in the two distributions indicate the areas at risk of colonization, with particular reference to Australia and the Americas. According to the model, the potential area of permanent colonization in Australia extends south to the mid-coast of New South Wales. Comparison of areas suitable for permanent establishment with the potential summer distribution indicates that large additional areas, carrying most of the continent's livestock, could be colonized in the summer months. Seasonal population growth indices are presented for three ports in Australia at which screw-worm fly specimens have been collected by quarantine authorities. They indicate the relative risk associated with introductions at different places in different seasons and so provide valuable planning information for quarantine authorities. The CLIMEX predictions for C.bezziana in North America are shown to be similar to the recorded distribution limits of the New World screw-worm fly, Cochliomyia hominivorax (Coquerel). The fly could also colonize South America, as far south as southern Brazil and midway through Argentina.