BIRDS VERSUS INSECTS.

Waikato Times, Volume 98, Issue 15312, 13 August 1923, Page 9

BIRDS VERSUS INSECTS.

STARTLING FIGURES.

Many people are quite unaware of the value of birds in helping to keep insects in their place, while others more familiar with the subject contend that the coming contest for supremacy is between man and insects and the depredations of the Bollwevil in the American cotton crops, which are being destroyed wholesale, to our mutual loss, is evidence of the insect's power. To prove what a menace insect life is, the remarks of an eminent authority on the subject arc quoted: Dr J. F. Illingworth, .Entomologist to the Queensland Sugar Bureau says, inter alia, in a report:—"Protection of the bird-life of a country is certainly worth considering, for we cannot begin to estimate their value to man, even those that we sometimes class as enemies when they occasionally eat our corn or kill our chickens. Undoubtedly, birds are the greatest factor in the control of insect pests. Theoretically, almost any minute insect, with its rapid method of multiplication, would over-run the earth, making it impossible for man or oilier animals to exist if the offspring of the insect all survived and reproduced. This has been forcibly illustrated by T. Bainbrigge Fletcher in his work on 'Some South Indian Insects,' when he takes the case of an insect laying only 200 eggs, and having a life-cycle of one month. Starting with Ist January for convenience, a single fertilised female lays 200 eggs, of which, on the average, half will be females, each of which will lay .20,0 eggs on February 1. By the end of February we have 100 x 200 —20,000 mature insects. Continuing, simple calculation shows that, by the end of the year, the descendants will reach the prodigious total of two septillions—2,ooo,ooo,000,000,000,000,000,000 of individuals. The human mind is quite incapable of grasping the significance of such a figure, but a few comparisons may assist the imagination. If 100 of the insects weighed only 1 oz, their united weight would be 558,035,718,571, 425.5 tons, and if 1000 measured one cubic inch they would cover an area of almost 50 billion square miles with a uniform layer, one inch deep. Taking the dry surface of the whole earth to be 51 millions of square miles, they would cover the whole of this to a depth of over 81 feet."

The above refers to the increase from one insect. There are computed to be 250,000 described species in the world, but leading authorities consider that only about 10 per cent have been found. That means that 2,250.000 species have yet to be described, should the above estimate be correct. Think over the above. The figures startle the average citizen, but they are correct. The three main contributing causes for the increase of insects are favourable climate, abundant food and freedom from enemies. Everything is nicely balanced in Nature, so that no species becomes predominant. Man, however, is often the means of upsetting this balance by transferring insects to new countries, where, removed from their natural enemies, they often become serious pests; or again, by cutting the forest he interferes with the nesting of insectivorous birds, e?,c, with the result that his crops are' destroyed until Nature is again able to maintain her balance. It is well recognised that man is able to greatly assist Nature in regaining this equilibrium. One way of doing this is by protecting, insectivorous birds, so that they will multiply near our homes. The easiest way of accomplishing this is by teaching the children. And the simplest way of teaching the children is by the introduction of "Bird "Day."