Ancient Inventions

Biological Pest Control

The Chinese were far ahead of the Western world in a natural pest control. In the countryside frogs were always a forbidden food because they ate insects. Praying mantises were released in gardens among the chysanthemums to drive away leaf-eating insects.

The most remarkable and economically important of the ancient Chinese biological weapons was the yellow citris killer-ant. Its use is described in Hsi Han's Records of the Plants and Trees of the Southern Regions, written in A.D. 340:

The Mandarin Orange is a kind of orange with an exceptionally sweet and delicious taste....The people of Chiao-Chih sell it in their markets [carnivorous] ants in bags of rush matting. The nests are like silk. The bags are all attached to twigs and leaves, which, with the ants inside the nests, are for sale. These ants do not eat the oranges, but attack and kill the insects which do. In the south, if the mandarin orange trees do not have this kind of ant, the fruits will be damaged by the many harmful insects, and not a single fruit will be perfect.

Defending orange trees against pests became a small business in southern China. In the twelfth century the ants were trapped by filling a pig or sheep bladder with fat and hanging it up next to an ants' nest. Once the ants had moved house to the bladder, it was taken off to market to be sold to fruit growers. To help the ants spread through an entire orange grove, the owners would build miniature bamboo bridges connecting the trees. With the current revival of interest in natural pesticides, perhaps the yellow citrus killer-ant may one day spread around the world—with a little help from humanity.

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