associate in their first or last state only, and those that associate in all their states. The first of these associations is often very short-lived: a patch of eggs is glued to a leaf; when hatched, the little larvæ feed side by side very amicably, and a pleasant sight it is to see the regularity with which this work is often done, as if by word of command; but when the leaf that served for their cradle is consumed, their society is dissolved, and each goes where he can to seek his own fortune, regardless of the fate or lot of his brethren. Of this kind are the larvæ of the saw-fly of the gooseberry, whose ravages I have recorded before[19], and that of the cabbage-butterfly; the latter, however, keep longer together, and seldom wholly separate. In their final state, I have noticed that the individuals of Thrips Physapus, the fly that causes us in hot weather such intolerable titillation, are very fond of each other's company when they feed. Towards the latter end of last July, walking through a wheat-field, I observed that all the blossoms of Convolvulus arvensis, though very numerous, were interiorly turned quite black by the infinite number of these insects, which were coursing about within them.

But the most interesting insects of this order are those which associate in all their states.—Two populous tribes, the great devastators of the vegetable world, the one in warm and the other in cold climates, to which I have already alluded under the head of emigrations—you perceive I am speaking of Aphides and Locusts—are the best examples of this order: although, concerning the societies of the first, at present we can only say that they are merely the result of a common origin and station: but those of the latter, the locusts, wear more the appearance of design, and of being produced by the social principle.

So much as the world has suffered from these animals[20], it is extraordinary that so few observations have been made upon their history, economy, and mode of proceeding. One of the best accounts seems to be that of Professor Pallas, in his Travels into the Southern Provinces of the Russian Empire. The species to which his principal attention was paid appears to have been the Locusta italica, in its larva and pupa state. "In serene warm weather," says he, "the locusts are in full motion in the morning immediately after the evaporation of the dew; and if no dew has fallen, they appear as soon as the sun imparts his genial warmth. At first some are seen running about like messengers among the reposing swarms, which are lying partly compressed upon the ground, at the side of small eminences, and partly attached to tall plants and shrubs. Shortly after the whole body begins to move forward in one direction and with little deviation. They resemble a swarm of ants, all taking the same course, at small distances, but without touching each other: they uniformly travel towards a certain region as fast as a fly can run, and without leaping, unless pursued; in which case, indeed, they disperse, but soon collect again and follow their former route. In this manner they advance from morning to evening without halting, frequently at the rate of a hundred fathoms and upwards in the course of a day. Although they prefer marching along high roads, footpaths, or open tracts; yet when their progress is opposed by bushes, hedges, and ditches, they penetrate through them: their way can only be impeded by the waters of brooks or canals, as they are apparently terrified at every kind of moisture. Often, however, they endeavour to gain the opposite bank with the aid of overhanging boughs; and if the stalks of plants or shrubs be laid across the water, they pass in close columns over these temporary bridges; on which they even seem to rest and enjoy the refreshing coolness. Towards sunset the whole swarm gradually collect in parties, and creep up the plants, or encamp on slight eminences. On cold, cloudy, or rainy days they do not travel.—As soon as they acquire wings they progressively disperse, but still fly about in large swarms[21]."

"In the month of May, when the ovaries of these insects were ripe and turgid," says Dr. Shaw[22], "each of these swarms began gradually to disappear, and retired into the Mettijiah, and other adjacent plains, where they deposited their eggs. These were no sooner hatched in June, than each of the broods collected itself into a compact body, of a furlong or more in square; and marching afterwards directly forwards toward the sea, they let nothing escape them——they kept their ranks, like men of war; climbing over, as they advanced, every tree or wall that was in their way; nay, they entered into our very houses and bed-chambers, like so many thieves.——A day or two after one of these hordes was in motion, others were already hatched to march and glean after them.——Having lived near a month in this manner——they arrived at their full growth, and threw off their nympha-state by casting their outward skin. To prepare themselves for this change, they clung by their hinder feet to some bush, twig, or corner of a stone; and immediately, by using an undulating motion, their heads would first break out, and then the rest of their bodies. The whole transformation was performed in seven or eight minutes; after which they lay for a small time in a torpid and seemingly in a languishing condition; but as soon as the sun and the air had hardened their wings, by drying up the moisture that remained upon them after casting their sloughs, they reassumed their former voracity, with an addition of strength and agility. Yet they continued not long in this state before they were entirely dispersed." The species Dr. Shaw here speaks of is probably not the Locusta migratoria.

The old Arabian fable, that they are directed in their flights by a leader or king[23], has been adopted: but I think without sufficient reason, by several travellers. Thus Benjamin Bullivant, in his observations on the Natural History of New England[24], says that "the locusts have a kind of regimental discipline, and as it were some commanders, which show greater and more splendid wings than the common ones, and arise first when pursued by the fowls or the feet of the traveller, as I have often seriously remarked." And in like terms Jackson observes, that "they have a government amongst themselves similar to that of the bees and ants; and when the (Sultan Jerraad) king of the locusts rises, the whole body follow him, not one solitary straggler being left behind