BIOLOGY, ECONOMIC, the application of biological science to the control and improvement of man's practical inter relations with plants and animals. Man's circle of practical inter ests intersects the life-circles of many other creatures. There are, first, those wild animals that are captured for food, and it is the business of economic zoology to make the most of such creatures as deer and antelopes, rabbits and hares, pigeons and partridges, frogs and food-fishes, squids and snails, cockles and mussels, oysters and clams, crabs and lobsters, shrimps and prawns, palolo worms and sea-cucumbers. Second, there are those animals cap tured, not for the food furnished directly by their flesh, but for other products, which are sometimes edible. Here are included baleen whales, elephants, beavers, birds of fine plumage, crocodiles for leather and turtles for combs, inedible fishes for glue and manure, oysters for pearls and beetles for blisters. Third, there are the animals that man has domesticated because of their direct or indirect utility—such as dog and horse, sheep and cattle, goats and reindeer, pigeons and poultry, ostriches and pheasants, silk moths and honey-bees. Here the modern biologist has to advise about the improvement of breeds.
Fourth, there are the animals that favour man's operations, like the earthworms that have made the fertile soil, and the flower visiting insects that secure cross-pollination. Here the main service of the economic biologist is to disclose and appreciate vital linkages that bind living creatures into an intricate system. Fifth, there are man's animal enemies, reduced in modern times both in numbers and size. Most of the beasts of prey have ceased to be important, but the poisonous serpent still bites man's heel. Of greater moment are man's parasites, such as hookworm and bil harzia, and the vehicles of parasites such as the malaria-carrying mosquito and the sleeping-sickness-carrying tsetse fly. The biolo gist has to unravel life-histories and discover checks and how best thou, may hP niit into nrartirc.
The sixth group is composed of animals which injure man in directly by attacking organisms that are useful to him, notably his animal stock and his crops. The list includes voles, wood pigeons, worm-parasites, locusts, cockchafers and cotton-weevils, wheat-midges and warble-flies. It is part of the task of the economic zoologist to combat these injurious animals, both di rectly and by encouraging natural checks. He has also to advise against operations that upset the balance of Nature and against careless importations and transportations. Seventh, there are animal enemies which injure man neither directly, nor through his stock and crops, but by getting at his stores or permanent pro ducts. Termites are very destructive in warm countries; rats and mice spoil much more than they eat ; weevils and their relatives destroy stored corn ; boring beetles eat away the rafters ; ship worms and boring crustaceans do much harm to wooden piers.
An eighth group consists of animals that are man's indirect friends, by keeping a check on the fifth, sixth and seventh groups, and must therefore be conserved and encouraged. The birds of prey keep down the voles ; the hedgehogs devour slugs ; lapwings feed on wireworms and leather-jackets; ichneumon-flies lay their eggs in caterpillars; spiders catch scale-insects; lady-birds levy toll on the green—flies; water-wagtails are fond of the small water snails that harbour the larval stages of the liver-fluke; and so on.
Similarly for plants, there are wild species directly used for food and drink; those that furnish valuable products like textiles and drugs; those that have been cultivated ; those that help man, as forests do in improving the climate. On the other hand, there are inimical plants like the "poison-ivy" and many bacteria ; the weeds that become pests and the moulds that attack crops ; the fungi that destroy stores and dry-rot wood.
The central idea of economic biology is that the circle of human life intersects many other circles; and these intersections, which are often changing, have to be controlled in man's interests —generously and far-sightedly interpreted. Man is part of a web of life in the weaving of which he increasingly shares, and the success of his weaving depends on his understanding, which in this particular case is expressed in economic biology. (See