But the Bruchus attacks more especially the seeds in our stores. Copying the Corn-weevil, who eats the wheat in our granaries and disregards the cereal swaying in the ear, in the same way she abhors the tender bean and prefers to make her home in the peace and darkness of our warehouses. She is a formidable enemy of the corn-chandler rather than of the farmer.
What a fury of destruction, once the ravager is installed amidst our hoards of beans! My [[229]]flasks proclaim the fact aloud. A single haricot-bean harbours a numerous family, often as many as twenty. And not only one generation exploits it, but quite three or four in the year. So long as any edible matter remains within the skin, so long do new consumers settle down in it, until in the end the haricot becomes a loathsome sugar-plum stuffed with stercoral droppings. The skin, which the grubs refuse to eat, is a sack pierced with round holes numbering as many as the inhabitants that have left it; the contents yield to the pressure of the finger and spread into a disgusting paste of floury excreta. The bean is a complete wreck.
The Pea-weevil, living alone in its seed, eats only enough to make a little hollow for the nymph. The rest remains intact, so that the pea is able to sprout and can even serve as food, if we dismiss any unreasonable repugnance from our mind. The American insect does not exercise this self-restraint: it empties its haricot entirely, leaving a skinful of filth which I have seen refused by the pigs. America does not do things by halves when she sends us her plagues of insects. We had to thank her for the Phylloxera, the disastrous Louse against whom our vine-growers wage incessant war; and now we have to thank her for the Haricot-weevil, a serious future menace. A few experiments will give us an idea of the danger.
For nearly three years there have stood, on the table of my insect laboratory, some dozens of jars [[230]]and bottles closed with gauze covers which prevent escape, while permitting constant ventilation. These are the cages containing my wild animals. In them I rear the Haricot-weevil, varying the diet as I please. They teach me among other things that the insect, far from being exclusive in the choice of its establishments, will make itself at home in our different legumina, with very few exceptions.
All the haricots suit it, whether black or white, red or striped, small or large, those of the last crop or those many years old and almost too hard to boil. The loose beans are attacked by preference, as being less troublesome to invade; but, when there are no shelled beans available, those covered by their natural sheath are just as zealously exploited. The new-born grubs are well able to reach them through the pod, which is often as stiff as parchment. This is how the beans are raided in the fields.
Another highly-appreciated bean is the long-podded dolichos, known among our people as lou faioù borgné, the one-eyed haricot, because of the dark speck which gives the umbilicus the look of a black eye. I even fancy that my boarders show a marked predilection for this bean.
So far, there is nothing abnormal: the Bruchus has not gone beyond the botanical genus Phaseolus. But here is something that increases the danger and shows us the phaseolus-lover in an unexpected [[231]]light. The Bruchus accepts without the least hesitation the dried pea, the broad bean, the everlasting pea, the vetch, the chick-pea; she passes from one to the other, always satisfied; her family live and prosper in all these legumina as well as they do in the haricot. Only the lentil is refused, perhaps because of its insufficient size. What a dread robber this American Weevil is!
The evil would become still greater if, as I feared at first, the ever-greedy insect passed from leguminous seeds to cereals. This it does not do. When installed in my jars with a heap of wheat, barley, rice or maize, the Bruchus invariably dies without offspring. The result is the same with horny seeds, such as coffee-beans; with oleaginous seeds, such as those of the castor-oil-plant or of the sunflower. Nothing outside the legumina suits the Bruchus. Notwithstanding these limitations, its portion is a very extensive one; and it uses and abuses it with the utmost energy.
The eggs are white and drawn out into a tiny cylinder. They are scattered anyhow and anywhere. The mother lays them either singly or in little groups, on the sides of the jar as well as on the haricots. Her heedlessness is such that she will even fasten them to maize, castor-oil-seeds, coffee-beans or other seeds, on which the family are doomed soon to perish, finding no food to their liking. What is the use of maternal foresight here? Left no matter where, under the heaps of beans, [[232]]the eggs are always well-placed, for it is the new-born grubs’ business to seek and find the spots at which to effect an entrance.
The egg hatches in five days at most. Out of it comes a tiny white creature, with a red head. It is a mere speck, just visible to the naked eye. The grub is swollen in front, to give more strength to its tool, the chisel of its mandibles, which has to break through the tough seed, hard as wood. The larvæ of the Buprestes and the Capricorns, which tunnel through the trunks of trees, are similarly shaped. As soon as it is born, the crawling worm makes off at random, with an activity which we should hardly expect in one so young. It roams about, anxious to find board and lodging as soon as possible.