I thought we might be overdue diptera so here are a pair of mating Yellow Dung Flies, Scathophaga stercoraria, at it hammer and tongs up on the Downs. The male is on top with the fancy golden hairy pantaloons. They are one of the commonest flies in the world, their distribution reflecting that of human animal husbandry.
They are also one of the most studied organisms in the world, lending themselves, like their prey and smaller cousins the fruit fly Drosophila melanogaster, to scientific experiment as a result of their rapid reproductive turnover.
The female lays her eggs on fresh dung and the larvae grow through three stages over five days. They then spend a further five days emptying their stomachs before burying down beneath the dung to pupate.
The young flies are anautogenous, which means they can't crack on with the sex until they've fed up for it.