“I don’t see anything, either,” said Jules. [[298]]
“Nor I,” added Louis.
“Those grains, boys, have no flour in them, despite their fair outside appearance; the weevil has emptied them.”
“But how can you tell so easily?” asked Jules.
“A kernel inhabited by the grain-weevil yields to the pressure of a finger and is also lighter in weight than one that is sound. From appearance alone one cannot tell infested kernels from uninjured ones, as the outside looks the same in both cases. Thus, without extreme vigilance, the inroads of the weevil pass unperceived until the developed insects show themselves; and then the evil is beyond remedy. Didn’t Simon think he had a fine lot of wheat when there was hardly anything but the bran left? A very simple experiment suffices to prove the condition of the wheat. Throw a handful of it into water and all the sound kernels will sink to the bottom, all the unsound ones float on the surface. We will perform this experiment with the wheat on the plate if Jules will go to the spring and bring a glass of water.”
The water was brought and Uncle Paul threw the wheat into it. A few grains sank, many floated. These latter were opened with the point of a pin, and in some was found a little soft white worm, without legs, but furnished with strong mandibles. It was the larva of the grain-weevil. In others there was a white nymph, and in a few was the perfect insect all ready to leave its snug abode.
“To judge by the number of grains that floated,” [[299]]Jules remarked, “Simon’s pile of wheat, even if it is not a very big one, must contain millions of weevils. It must have taken a lot of the creatures to produce such an immense family, mustn’t it?”
“Not so many as you might think. How many eggs do you suppose one weevil lays?”
“A dozen, perhaps.”
“Ah, how far out you are in your reckoning! In the course of one season a weevil lays from eight to ten thousand eggs, from which spring as many larvæ, each gnawing a grain. A liter measure[1] contains, on an average, ten thousand grains of wheat. To feed the family of one weevil, therefore, nearly a liter of wheat is needed. Suppose there are a thousand pairs of these insects in a granary; that would be enough to destroy ten hectoliters of wheat, rye, barley, or oats; for they attack all kinds of grain impartially.” [[300]]