CLASS V.—INSECTS.
256. The SPANISH FLY, or BLISTERING LYTTA (Lytta vesicatoria), is a coleopterous insect ([12]), about an inch in length, of shining blue-green colour with black antennæ.
It is found in most parts of Europe, and feeds on the leaves of the ash, poplar, elder, lilac, and other trees.
These insects, which are known in medicine by the name of cantharides, are of incalculable importance to mankind, as the basis of blistering plasters, and also as an internal remedy against many diseases. We import them in a dried state, from Spain, Italy, and the South of France; in many parts of which countries, about the middle of summer, they are found in vast abundance. As they are generally in a torpid state during the day, they are easily collected, by shaking them from the trees upon a cloth spread on the ground to receive them. When a sufficient number has been collected they are tied in bags, and killed by being held over the fumes of hot vinegar. After this they are dried in the sun, and packed in boxes for sale. The odour which is emitted by these insects is peculiarly nauseous, and so powerful, that great injury has sometimes been experienced by persons employed in picking them, and by those who have even fallen asleep under the trees where they abound.
Previously to being used they are pounded; and if, in this state, they be applied to the skin, they first cause inflammation, and afterwards raise a blister. The usual blistering plaster is formed with Venice turpentine, yellow wax, Spanish flies, and powdered mustard.
257. The PALM-TREE GRUB, or GRUGRU, is the larva or caterpillar of a coleopterous insect ([12]), the palm-tree weevil (Curculio palmarum), which is about two inches in length, of black colour, and has the elytra or wing cases shorter than the body, and streaked or marked with several longitudinal lines.
This insect is found in Cayenne, Surinam, and other parts of South America.
It deposits its eggs on the summit of the palm-tree; and the grubs that issue from these eggs subsist on the soft interior parts of the tree. They become about the size of the thumb, and are much sought after in many places for the table. They are generally eaten roasted, and are considered a peculiar delicacy. We are informed, by Ælian, of an Indian king, who for a dessert, instead of fruit, set before his Grecian guests a dish of roasted worms taken from a plant: these were probably the present insects, or a kind nearly allied to them.