Speaking of exotic tastes one should not forget the coprophagous animals, which do a great deal of good (kopros is the Greek for dung, phagos means one who devours).
Many animals only resort to eating excrements for a short time. For instance, some of the dog family will eat the faeces of their offspring while they are very young. This is, no doubt, for the sake of hygiene, to ensure cleanliness in the den.
The dung-eating habit of the larva of the honeycomb moth which usually feeds on beeswax is extremely interesting. But, if voracious creatures have already succeeded in destroying a bee nest completely and devouring all the wax, the larvae have to eat their own excrements which have accumulated by that time in excess. The surprising thing is that the new excrements also prove edible. More than one generation of honeycomb moth can thus grow up feeding on their own excrements and eating them up again. This peculiar cycle may sometimes last for seven or eight years.
The explanation for this everlasting replenishment of energy resources, which has something in common with perpetuum mobile, is simple. Beeswax is a substance which is extremely hard to digest. Even in the intestines of the honeycomb moth, which is adapted to feeding exclusively on beeswax, it is never digested completely. This explains the efficacy of the repeated processing of excrements.
Our Earth is also inhabited by large numbers of permanently coprophagous creatures. Some beetles, mites and worms feed solely on dung. Among them are some which will eat only cow, horse or hare dung. Of special interest are dung beetles, which dig small burrows beneath dung heaps and fill them up with food supplies for future larvae.
The sacred scarabs are puzzling in that they roll the dung up into balls which are many times larger than they themselves. It was not without reason that the ancient Egyptians thought these beetles to be sacred and worshipped their graven images. Every Apis, a sacred bull which lived in the temple of Memphis, had an image of this natural sanitary worker painted on its body.
Red wood ants normally live exclusively on the excrements of aphides which contain sugar and other nutrients. The ants not only gather the excrements, they also protect the aphides against their enemies, breed them and tend them. In the autumn the ants search for the winter eggs of the aphides and hide them in their ant-hills. When spring comes and it gets warm, these toilers drag the young aphides out onto the grass and pasture them. Every evening the ants carry them ‘home’ until the nights grow warm enough for them to stay outdoors. Some ants breed aphides that live on roots and build for them miniature sheds of earth. In one year a single ant-hill collects about one hundred kilograms of aphides’ excrements.