Studies of British Anthomyiid Flies

Abstract

Observations have been made on the life-history and habits of C. cilicrura. The flies came to moist, freshly turned soil at all times from April to October, particularly in warm bright weather, but the number of flies seen on observation plots was affected by the area of damp and disturbed soil nearby. Both males and females were attracted and some females laid eggs within a few minutes of their capture. When isolated in phials and fed on dilute sugar solution, captured flies lived up to 79 days. Captured females spent varying periods up to 44 days before laying eggs. The eggs were usually laid in batches of less than ten at irregular intervals over periods extending up to 28 days, and 53 eggs per fly was the highest number recorded. Parasitism by the nematode, Heterotylenchus aberrans Bovien, occurred.Eggs were found in soil crevices and on vegetation in contact with soil. The observed incubation period was 2–4 days according to the temperature.The duration of the larval instars was affected by temperature; in captivity, the larval feeding period was 8–16 days in May-June and 15–24 days in October-November. The pupal stage lasted from 16–21 days in May-June and from five weeks to five months in autumn and winter. A few flies emerged during January and February in the insectary.In captivity first-instar larvae found food buried at a depth of 6 ins. and they were able to reach maturity on fragments of vegetation buried in sand. It is suggested that they are primarily scavengers on organic matter in the soil.Larvae of P. fugax have been found in the stems and crowns of turnips and swedes, and in cabbages, cauliflowers, lettuces and brussels sprouts. A study of their habitat shows that they occur in decomposing vegetation.Eggs have been found about various brassicas. Their incubation period was 2–4 days. Larvae were reared in decomposing vegetation. Pupation takes place in the soil and in the feeding sites. Adults have been taken from May to October. The life-cycle from egg to adult occupied 4–5 weeks in spring and the winter was passed in the pupal stage.