The black soldier fly Hermetia illucens already numbers millions in Britain, but if you meet one in the wild it will have escaped. It is of the newest and most productive creatures farmed in these islands. So far it is being kept in controlled conditions so that its larvae can be fed to a large variety of pets – reptiles and birds, but mostly fish.
The most ambitious projects involve feeding the maggots on tons of waste food and then using the larvae as the main source of protein for fish farms. The attraction is that the larvae grow incredibly fast, gaining up to 5,000 times their own body weight in a couple of weeks. The larvae contain a large array of nutrients absorbed from the food that would otherwise be dumped.
Using fly farms as fodder for the fish farming industry would also avoid the destructive practice of catching tons of wild fish in South America to be converted into fishmeal pellets to feed to salmon in Europe. Black soldier flies are quite large, at 16mm (5/8in) long, but harmless. They prefer slightly warmer climes than Britain, but as the climate warms the soldier’s range is creeping north and it is already common in France.
