Termite queens in the East Indies are given alive to old men for strengthening the back.[471] Ephemeridæ--Day-flies. The name of Ephemeridæ has been given to the insects, so called, in consequence of the short duration of their lives, when they have acquired their final form. There are some of them which never see the sun; they are born after it is set, and die before it reappears on the horizon. These insects, indifferently called also Day-flies and May-flies, usually make their appearance in the districts watered by the Seine and the Marne, in the month of August; and in such countless myriads, that the fishermen of these rivers believe they are showered down from heaven, and accordingly call the living cloud of them _manna_--manna for fish, not men. Reaumur once saw them descend in this region so fast, that the step on which he stood by the river’s bank was covered by a layer four inches thick in a few minutes. He compares their falling to that of snow with the largest flakes.[472] Scopoli assures us that such swarms are produced every season in the neighborhood of some particular spots in the Duchy of Carniola, that the countrymen think they obtain but a small portion, unless every farmer can carry off about twenty cartloads of them into his fields for the purpose of a manure.[473] Libellulidæ--Dragon-flies. On account of the long and slender body, peculiar to the insects of this family, they are with us sometimes called _Devil’s Darning-needles_, but more commonly _Dragon-flies_. In Scotland they are known by the name of _Flying Adders_, for the same reason. The English, from an erroneous belief that they sting horses, call them _Horse-stingers_. In France, from their light and airy motions, and brilliant, variegated dress, they are called _Demoiselles_; and in Germany, for the same reason, and that they hover over, and lived during their first stages in, water, _Wasser-jungfern_--Virgins of the Water. Another German name for them is _Florfliegen_--Gauze-flies, in allusion to their net-like wings. Our boys also call them _Snake-feeders_ and _Snake-doctors_, in the belief that they wait upon snakes in the capacity of feeders and doctors; and so firm are they in this belief, that frequently I have been laughed at for asserting the contrary to them. The belief probably arose from the manner in which the Dragon-fly sometimes falls a prey to the snakes. Hovering over ponds, they are fond of alighting on little sticks and twigs just out of the water, and mistaking the heads of snakes, which probably swam there for the purpose, for such twigs, they are instantly caught by the snakes.