One of the downsides of a heat wave are the flies and flying insects that suddenly appear. There are vast numbers of different species of fly - each one having its own distinct life cycle and home. At the moment it’s fruit flies, sometimes called vinegar flies, that are in abundance. They thrive on the fruit and vegetable remains in compost bins that, on a hot summer’s day, start to break down into a semi-liquid soup. The tiny yellowish brown flies with bright red eyes will appear almost overnight and great clouds of them can erupt from unsealed compost bins.