1769, and arrived at its height in 1783, when the number of trees destroyed by it in the above-mentioned forests alone was calculated at a million and a half, and the whole number of insects at work at once one hundred and twenty thousand millions. The inhabitants were threatened with a total suspension of the working of their mines, for want of fuel. At this period these Bostrichi, when arrived at their perfect state, migrated in swarms like bees into Suabia and Franconia. At length a succession of cold and moist seasons, between the years 1784 and 1789, very sensibly diminished the numbers of this scourge. In 1790 it again appeared, however, and so late as 1796 there was great reason to fear for the few fir-trees that were left.[191]
Cantharidæ—Blister-flies.
Many species of this family of insect possess strong vesicating powers, and are employed externally in medicine to produce blisters, and internally as a powerful stimulant. Taken internally, Pliny considered them a poison, and mentions the following instance of their causing death: Cossinus, a Roman of the Equestrian order, well known for his intimate friendship with the Emperor Nero, being attacked with lichen, that prince sent to Egypt for a physician to cure him; who recommended a potion prepared from Cantharides, and the patient was killed in consequence.[192] But there is no doubt, however, Pliny adds,
that applied externally they are useful, in combination with juice of Taminian grapes, and the suet of a sheep or she-goat. They are extremely efficacious, too, continues Pliny, for the cure of leprosy and lichens; and act as an emmenagogue and diuretic, for which last reason Hippocrates used to prescribe them for dropsy.[193]
The vesicatory principle of the Blister-fly is called Cantharidine, and has been ascertained by experiment to reside more particularly in the wings than in other parts of the body. Our officinal insect is the Cantharis vesicatoria; and since the principal supply is from Spain, we call them commonly Spanish-flies. In Italy, the Mylabris cichorii, a native of the south of Europe, is used; and the M. pustulata, a native of China, is used by the Chinese, who also export it to Brazil, where it is the only species employed. In India also a species of Meloe is used,[194] possessing all the properties of the Spanish-fly.
At one time in Germany, the genus Meloe—Oil-beetles (so called from their emitting from the joints of the legs an oily yellowish liquor, when alarmed)—were extolled as a specific against hydrophobia; and the oil which is expressed from them is used in Sweden, with great success, in the cure of rheumatism, by anointing the affected part.[195] Dr. James thus enumerates the medicinal virtues of these insects: “The Oil-beetle (Scarabæus unctuosus of Schroder) is much of the nature of Cantharides, forces urine and blood, and is of extraordinary efficacy against the bite of a mad dog. Taken in powder, it cures the vari, or wandering gout, as we are assured by Wierus. The liquor is, by some, esteemed of efficacy in wounds; it is an ingredient also in plaisters for the pestilential bubo and carbuncle, and in antidotes; an oil is prepared by infusion of the living
animals in common oil, which some use instead of oil of Scorpions.”[196] In some parts of Spain, they are mingled with the Cantharides, for the same purposes as these latter insects. Farriers also employed, in some cases, oil in which these insects had been macerated.[197]
Pliny tells us that Cato of Utica was one time reproached for selling poison, because when disposing of a royal property by auction, he sold a quantity of Cantharides, at the price of sixty thousand sesterces.[198]
The natives of Guiana and Jamaica make ear-rings and other ornaments of the elytra, or wing-coverings, of the Cantharis maxima; the brilliant metallic colors of which beetles, says Sloane, sparkle with an extraordinary lustre, when worn by the Indians dancing in the sun.[199]
Zoroaster says, that “Cantharides” will not hurt the vines, if you macerate some in oil, and apply it to the whetstone on which you are going to set your pruning-knives.[200]