My primary source for the French silk industry in 1892, Albert de la Berge, (the Chautauquan, vol 12,1892) wonders why, "Considering the simplicity of the operation, the little capital and the short time required...sericulture is not more a more widespread and prosperous employment. It was in France for a long time...very lucrative but then and there the conditions were favorable to it which is not the case now in France.The sericulturists who remember the ancient prosperity of their industry and the good price the silk cocoons brought are convinced that the two elements are inseparable.They seem not to care about a new demand for the product unless there is also a rise in the price of silk."
De la Berge complains that because the price of silk had fallen, farmers refused to replant their mulberry plantations. The only business strategy they could understand, he despairs, was to restrict supply to keep prices high. If prices were not high, then why invest in silk? The farmers evidently did not consider what was obvious to de la Berge: that they could make as much profit by selling more silk (a possibility with modern advances.)
Meanwhile, disaster had struck the silk industry. An 1882 Popular Science article explained that "the revenue from silk-culture had doubled itself during the twenty years before 1853, and appeared at that time likely to continue to increase. Then disaster suddenly fell on the business, and the production of cocoons fell from twenty-six million kilogrammes in 1853, in the course of twelve years, to four million kilogrammes, the fall entailing, in the single year last mentioned, a loss of one hundred million francs, or twenty million dollars."
Some unknown disease was devastating the silk industry. Farmers cut down their mulberry plantations.
Scientist Louis Pasteur (1822 - 1895) was recruited to help to identify the cause of the blight, and through careful observation, in 1865 he identified two diseases, pébrine and flacherie. When challenged by skeptics, he proved his point by using his microscope to examine fourteen batches of eggs. He correctly predicted which batches were contaminated.
Pébrine, is "outwardly manifested by black spots on the bodies of the caterpillars, and also declared itself in their stunted and unequal growth, the languor of their movements, their fastidiousness towards food, and their premature death." (Popular Science, 1882.) Pasteur identified the cause as a a parasite. A silkworm would pick up the parasite by ingesting an infected mulberry leaf and, metamorphosized into a moth, passed it on to her eggs. The silk worms hatching from the infected eggs would die in the larva stage.
Flacherie, "flaccidness" results when silkworms eat contaminated mulberry leaves. They are infected with a deadly virus that destroys their gut tissue.
Having identified the diseases ravaging the silk industry, scientists were able to identify remedies, but it was too late. The silk industry never fully recovered; World War I finished it off.
The amazing thing to consider, however, is that the destruction of the silk worm industry (which began around 1850) was followed within a decade by the phylloxera blight and the destruction of the French wine industry. De la Berge writes that "the French in the southeast like the Egyptians of long ago have passed through an extraordinary succession of fat years and lean years. It is easy to recall the comfort and even the riches which reigned in the valley of the Rhone forty years ago. The diseases of the silk worm had not then come to ravage the hatcheries, the discovery of alizarine had not destroyed the madder, the vine which did not know the phylloxera (an insect which attacks the grape vine) bore superb crops."
"All the scourges swept down upon them at the same time, the pébrine and flachery, diseases of the silk worm, the mildew and phylloxera. The husbandman became discouraged. He cut down many mulberry trees and neglected planting any new ones. So the comparatively few left are now very old and feeble and unable to resist parasites and insects, cold and drought. The new plantations set out recently have been used too soon so that the trees are arrested in their development. In short, the supply of trees is altogether insufficient both as to quantity and quality so much so that the leaves today cost half as much as the cocoons sells the fibers."
The photos are self-evident: silk moth, caterpillar & cocoon, silk, moth, silk moth--the first three all the same type. The yellow moth is a different kind of silk moth. And the last two are more silk moths. The moths are bigger and prettier than I expected.