One of the authors here alluded to is our homely immortal, White of Selborne. “I shall here mention,” he says, “an emigration of small Aphides, which was observed in the village of Selborne no longer ago than August 1st, 1785. At about three o’clock in the afternoon of that day, which was very hot, the people of this village were surprised by a shower of Aphides, or smother-flies, which fell in these parts. Those that were walking in the streets at that juncture found themselves covered with these insects, which settled, also, on the hedges and gardens, blackening all the vegetables where they alighted. My annuals were discoloured with them, and the stalks of a bed of onions were quite coated over for six days after. These armies were then, no doubt, in a state of emigration and shifting their quarters; and might have come, as far as we know, from the great hop-plantations of Kent or Sussex, the wind being, all that day, in the easterly quarter. They were observed, at the same time, in great clouds about Farnham, and all along the vale from Farnham to Alton.”[38] Other great migrations of Aphides have at various times been observed. In the autumn of 1834 the city of Gand was invaded, and, one may almost say, taken by a vast army of them, and at Bruges and Antwerp the same swarm is said to have darkened the sun,[39] a result of such gatherings more noticeable elsewhere than in England, since our sun usually is darkened. Insects, though their movements are not so regular, nor, as a rule, so noticeable as those of birds, yet often migrate—how often or how regularly it is difficult to say. Locusts are, of course, the stock example as well as the most terrific one, but perhaps dragon-flies, were they as destructive, would have been as much noted in this connexion. Their migrations seem to be tolerably frequent, and a record of them between 1494 and 1868 has been published by Koppen, a German entomologist. In 1881 a great flight of them took place in Illinois. “The air,” we are told, “for miles around seemed literally alive with these dragon-flies, from a foot above ground to as far as eye could reach, all flying in the same direction, a south-westerly course, and the few that would occasionally cross the track of the majority could all the more easily be noticed from the very regular and swift course they generally pursued; but even these few stray ones would soon fall in with the rest again. Very few were seen alighting and all carefully avoided any movable obstacles.”[40] This migration took place during a very dry season, and may have been caused by it owing to the drying up of swamps, ponds, etc., in which the insects would otherwise have laid their eggs, obliging them to seek other suitable places.