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Dr. Walter B. Collinge



were marshalled in line with ten to a linear inch and touching one

another, “ the procession would extend to the sun (a space which

light traverses in eight minutes), and beyond it to the nearest fixed

star (traversed by light only in six years), and still onward in space

beyond the most distant star that the strongest telescope may bring

to view, to a point so inconceivably remote that light could only

reach us from it in twenty-five hundred years.”


But there is scarcely a cultivated plant that is not attacked by

one or more species of greenfly, or aphid as the naturalist terms them.

Of the trillion of billions that infest the apple, pear, plum and cherry

trees, and the hops, wheat, beans, turnips, cabbage, etc., what

becomes of them ? They are eaten by the birds. Aphids in large

quantities have been found in the stomachs of the Whitethroat, the

Warblers, the Tits, the Wren, the Goldfinch, the Chaffinch, the Sky¬

lark, and numerous other birds ; and the same remarks hold good

with reference to the insidious Scale Insects.


Most insects do the greatest amount of damage during their

larval or caterpillar stage ; they feed voraciously, their daily con¬

sumption of food often exceeding many times the weight of their

bodies. Selecting a familiar example, the yellow-and-chocolate

marked caterpillar of the Currant or Magpie Moth, it requires about

170 of these to weigh an ounce ; in their earlier stages say about 200.

We have seen currant plantations infested with these, and by counting

the number on one bush have estimated nearly 1,000,000 to the

plantation, or a total of 2J cwt. Had these been left undisturbed

they would quickly have consumed the whole of the currant-leaves

and ruined the crop, but thanks to the birds they were reduced to

insignificant dimensions long ere they had an opportunity of devas¬

tating the bushes. And so it is with numerous other crops. We

might continue to cite insect after insect and the birds that feed upon

them, but one further case will suffice.


Trouvelot, who introduced the Gipsy Moth into the United

States of America, specially studied the American silkworm, and

respecting its food and rate of growth he made numerous experiments.

The rate of growth and the amount of food consumed are astonishing.

Upon hatching from the egg, the caterpillar weighs one-twentieth of

a grain ; when 10 days old its weight has increased to half a grain



