Abstract

Over three summers (1993-94, 1996 and 1996-97), four fly-traps were placed at each of two locations on Massey University farms. Caught flies comprised eight species, of which four are commonly involved in flystrike. Australian sheep blowfly (Lucilia cuprina) numbers caught varied dramatically between years. At the season peak, numbers in 1996 and 1996-97 were three and one and a half times higher, respectively, than in the first year. Average weekly fly catch increased rapidly over a 2-3 week period from near zero to a peak (in years 1996 and 1996-97) of about 30 flies for L. cuprina and from near zero to a peak (in 1996-97) of about 75 flies for Chrysomya rufifacies in February/early March. Peaks presumably reflected emergence of adult flies from the previous year’s pupae that overwintered in the soil. Five of the eight species showed a second peak about four weeks after the first. The second peak most likely reflects emergence of a second generation. Minimum temperature explained a significant proportion of variation (up to 48%) in fly numbers. Rainfall and wind run were less important. Further work is required to provide robust indicators of potential rises in fly numbers.

YH, Cottam, HT Blair, and MA Potter

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 220-223, 1998