Yellow dung flies are Diptera (true flies) which eat other insects and also feed on nectar. After mating, the females lay their eggs on the surface of a dung pat. In UK, they are a common sight on and around fresh cattle dung, but they can also use horse and sheep dung. The eggs hatch into larvae (maggots) and these pupate in the dung pat. Three weeks after the egg was laid, adults emerge and after a further three weeks, these mate and lay eggs. So egg-to-egg time is about six weeks and there may be 3-5 broods a year. Many other insects - flies and beetles - use dung as a source of food or a place to develop.

Mesembrina            Yellow dung fly

> The timing of the spring peak.

> Whether some flies over-winter as adults.

> What is the effect of modern farming methods.

> Whether numbers are declining.

Yellow dung flies are about the same size as house flies. The males are the only yellow flies found on a

dung pat, being covered in bright yellow hairs. There may be up to eighty on one pat. Blow flies are a similar size but have metallic or grey / brown colours. You may see the large spectacular Mesembrina, with its orange wing patches. You will also see lots of smaller flies, perhaps dung beetles and on older pats, even spiders.

Yellow dung flies hatch in the early spring and are ready to mate as soon as the cattle are turned out. Following a spring peak, there is a lull in the summer, especially when it is very hot. There is then another peak in the autumn and some flies can still be found even in cold weather.