MILKING IT

Female louse flies nurse their young internally.

Fly milk is similar to mammalian milk in many ways. It is a creamy concoction of fats, proteins and symbiotic bacteria. That last ingredient is particularly important in the gut of parasitic flies. This is because the bacteria can synthesise

essential vitamins and other nutrients not found freely in the blood of the host.

Once the maggot has completed its development, nourished entirely by the milk, it is ejected into the world by its mother. She is, effectively, a fly in labour!