Seasonal abundance during the summer months of some cattle‐visiting Muscidae (Diptera) in northeast England

Abstract

Abstract. 1. Regular samples of flies swarming around cattle in Northumberland, England, were collected from late May to early October 1980–82, during weather judged to be suitable for fly activity. 2. Results were grouped into weekly periods and averaged to reduce variation caused by the weather. 3. For all species of Muscidae that were caught in reasonable numbers, the changes in abundance through the season are described. 4. The proportion of each species in the total sample is discussed; biting species were not sampled as efficiently as were non‐biting species. Hydrotaea trritans and Morellia simplex were the most numerous species forming 49% and 32% of the catch respectively. 5. The total numbers of flies were low at the beginning of the sampling period, rose to a maximum in mid‐July, stayed high until mid‐September and then declined by October.

Chromosomal Variation, Segregation and Sex Determination in Hydrotaea Meridionalis (Diptera: Muscidae)

“…The skewed ratio recorded could be simply due to behavioral differences between the sexes. In a very closely related species, Hydrotaea irritans, also showing rather skewed sex-ratios in samples of adults from natural populations (BALL 1984;and unpubl. results), the sex-ratio has been close to 1:l among more than hundred offspring reared from eggs of hand-netted flies and hatched in the laboratory, and no observation of any distortion mechanism has been made (G. THOMAS, pers.…”