vision. When at rest, therefore, it is doubled up by means of its joint, and lies in a very small compass, the first portion being brought within the lip, and a second part folded under the head and neck. It is altogether different then from the tubular sucking tongue of a fly, being imperforate and only fitted for lapping; while the insect is at the same time furnished with mandibles of similar structure to those of the eating insects described in the preceding chapter.

Having thus entered so minutely into the structure of the tongue of the bee, it will be unnecessary to describe in detail the similar organs of some other families, more particularly as these seem to be of inferior interest, at least so far as we have examined them. The wasps (Vespide), which so nearly resemble bees both in habits and in general appearance, are greatly different in the development of these organs, the tongue being small, while the mandibles, on the other hand, are large, and more like the insects which we have considered in the preceding chapter as exclusively eaters. They are accordingly better known for their depredations on fruit, than for feeding in the manner of bees; yet are they very fond of sweet things, since they will plunder beehives of their honey (though they will not take the trouble of collecting it from flowers), and they frequently devour great quantities of sugar. Kirby tells us, that a tradesman of his acquaintance calculated his loss of sugar in one year, by wasps alone, at twenty pounds sterling*, Wasps, besides, are insects of prey, and in France, Réaumur says, the butchers are glad to have wasps attend their stalls for the sake of their services in driving away the blow-flies; for a similar purpose the Americans sometimes suspend a hornet's nest in their parlour†. * Intr. i, 228, + St. John's Letters of an American Farmer,

177

CHAPTER VIII.

SUCKING INSECTS.

WE have elsewhere remarked that, "the beak (haustellum) of an aphis is no more fitted for lapping honey-dew, than the bill of Esop's crane was for eating out of a shallow plate*.' The mere inspection of one of these insects with a pocket magnifier will be sufficient to demonstrate the position; but, for the sake of illustration, we shall give a few details, and for that purpose we shall select the brown aphis of the oak (Aphis Quercus, LINNæus), in which, from its being much larger than its congeners, the parts are more conspicuous. The sucker in this insect is much longer than the body, and, when unemployed, is carried between the legs close to the belly, extending behind the insect, like a tail slightly curved upward. The instrument consists of a transparent tube, terminating in a hole so minute, that Réaumur could not discover it with his most powerful microscopes, but easily proved its existence by pressing out from it a drop of fluid. By means of pressure, also, he could render more obvious two instruments of a brownish colour contained in the sucker, and which he conjectured to act like the piston of a pump; though from their minuteness this. could not be correctly ascertained. We might suppose them to act as perforators, were it not that the point of the sucker itself seems sufficiently adapted to that purpose. The figures which we have here given will render our description easily understood.

*Insect Transf. p. 18.

Aphis Quercus. a, real size, showing the sucker bent under it like a tail; b, magnified; c, sucker magnified,

With so efficient an instrument for wounding plants, we need not wonder that a race so countlessly numerous as the aphides effect most destructive ravages in the vegetable kingdom. The serious ravages of the dolphin, or collier (Aphis Faba), on the bean crop, and of the hop-fly (A. Humuli) in hopgrounds, are but too well known. Of late years another of these pests, called the American, or white, blight (Aphis lanigera, ILLIGER; Eriosoma Mali, LEACH), has been extensively destructive to our apple-trees. According to Mr. Knapp's information,

it was first observed in the West of England, in 1819, in the nursery gardens of Messrs. Millar and Sweet, near Bristol, introduced, as was supposed, by some imported plant*. Salisbury, on the other hand, says, "I have from good authority heard that it was brought to this country from France in the reign of Louis XIV., when a colony of refugees settled at Paddington, and there it was first observed to begin its depredations on the apple-trees.

I am in some measure warranted in my belief, that the insect in question was introduced from France, as an old French gardener who worked in my garden stated that he was well acquainted with the bug, as he termed it, since his childhood, and that it had been the destruction of many fruits, not apples in particular, in the neighbourhood of Montpelier, where he had been brought up*" We have ourselves seen the insect in the orchards about Harfleur, in Normandy†; and M. Blot informs us that it is exceedingly destructive to the apple-trees in the department of Calvadost.

Sir Joseph Banks traced the supposed first appearance of the insect to a nursery in Sloane-street, Chelsea; and, upon being informed that it was unknown in France, concluded that it was most probably imported from North America, with some appletrees which had been brought over to that nursery. But, in whatever way it originated, it spread rapidly, though it was at first confined to the vicinity of the metropolis, where it destroyed thousands of trees §. Subsequently it found its way into other parts of the kingdom, and, in 1810, so many of the cyder appletrees in Gloucestershire were infested with it, that it was apprehended the making of cider would have to be abandoned.

66

The particular history of the insect is well given by Mr. Knapp. "In the spring of the year," says he, a slight hoariness is observed upon the branches of certain species of our orchard fruit. As the season advances, this hoariness increases; it becomes cottony, and, toward the middle or end of summer, the under sides of some of the branches are invested with a thick, downy substance, so long, as at times to be

*Hints on Orchards, p. 39.
† J. R.
Mem, Société Linn. de Caen pour 1824, p. 104.
§ Trans, Hort. Soc., ii, 162.