LETTER XCVI.

TO THE HON. DAINES BARRINGTON.

SELBORNE, September 9, 1781.

I HAVE just met with a circumstance respecting swifts, which furnishes an exception to the whole tenor of my observations ever since I have bestowed any attention on that species of hirundines. Our swifts, in general, withdrew this year about the first day of August, all save one pair, which in two or three days was reduced to a single bird. The perseverance of this individual made me suspect that the strongest of motives, that of an attachment to her young, could alone occasion so late a stay. I watched therefore till the twenty-fourth of August, and then discovered that, under the eaves of the church, she attended upon two young, which were fledged, and now put out their white chins from a crevice. These remained till the twenty-seventh, looking more alert every day, and seeming to long to be on the wing. After this day, they were missing at once; nor could I ever observe them with their dam coursing round the church in the act of learning to fly, as the first broods evidently do. On the thirty-first, I caused the eaves to be searched; but we found in the nest only two callow, dead, stinking swifts, on which a second nest had been formed. This double nest was full of the black shining cases of the hippobosca hirundinis.

The following remarks on this unusual incident are obvious: The first is, that though it be disagreeable to swifts to remain beyond the beginning of August, yet that they can subsist longer is undeniable. The second is, that this uncommon event, as it was owing to the loss of the first brood, so it corroborates my former remark, that swifts breed regularly but once; since, was the contrary the case, the occurrence above could neither be new nor rare.

P.S. One swift was seen at Lyndon, in the county of Rutland, in 1782, so late as the 3d of September.

LETTER XCVII.

TO THE HON. DAINES BARRINGTON.

As I have sometimes known you make inquiries about several kinds of insects, I shall here send you an account of

one sort which I little expected to have found in this kingdom. I had often observed that one particular part of a vine, growing on the walls of my house, was covered in the autumn with a black, dust-like appearance, on which the flies fed eagerly; and that the shoots and leaves thus affected did not thrive, nor did the fruit ripen. To this substance I applied my glasses, but could not discover that it had any thing to do with animal life, as I at first expected; but upon a closer examination behind the larger boughs, we were surprised to find that they were coated over with husky shells, from whose sides proceeded a cotton-like substance, surrounding a multitude of eggs. This curious and uncommon production put me upon recollecting what I have heard and read concerning the coccus vitis vinifera of Linnæus, which, in the south of Europe, infests many vines, and is a horrid and loathsome pest. As soon as I had turned to the accounts given of this insect, I saw at once that it swarmed on my vine: and did not appear to have been at all checked by the preceding winter, which had been uncommonly severe.

Not being then at all aware that it had any thing to do with England, I was much inclined to think that it came from Gibraltar, among the many boxes and packages of plants and birds which I had formerly received from thence; and especially as the vine infested grew immediately under my study window, where I usually kept my specimens.* True it is, that I had received nothing from thence for some years but as insects, we know, are conveyed from one country to another in a very unexpected manner, and have a wonderful power of maintaining their existence till they fall into a nidus proper

Most of the species of coccus, which are found in and infest the green-houses and conservatories of Britain, have been introduced with exotic plants. They are now very cominon in this country, and are a very prolific race. The females fix themselves, and tenaciously and immoveably adhere, to the branches of plants. Some of them lose entirely the form of insects: their bodies swell, their skin stretches, and becomes smooth, and they so closely resemble some of the galls, or excrescences, found on plants, as to be taken for such by people unacquainted with the subject. After this change, the abdomen serves only as a kind of shell, or covering, under which the eggs are concealed. Others, although they are also thus fixed, preserve their insect form till they have laid their eggs, and then die. A kind of downy substance grows on their abdomen, which serves for the formation of the nest in which they deposit their eggs. The males differ considerably from the females, being provided with wings, and are small, but very active insects. It is from one of this tribe, the coccus cacti, or American cochineal, that the celebrated red dye called cochineal is made. - ED.

for their support and increase, I cannot but suspect still that these cocci came to me originally from Andalusia. Yet, all the while, candour obliges me to confess, that Mr Lightfoot has written me word, that he once, and but once, saw these insects on a vine at Weymouth, in Dorsetshire; which, it is here to be observed, is a seaport town to which the coccus might be conveyed by shipping.

As many of my readers may possibly never have heard of this strange and unusual insect, I shall here transcribe a passage from a Natural History of Gibraltar, written by the Reverend John White, late vicar of Blackburn, in Lancashire, but not yet published :

66

The tree

In the year 1770, a vine, which grew on the east side of my house, and which had produced the finest crops of grapes for years past, was suddenly overspread, on all the woody branches, with large lumps of a white fibrous substance, resembling spiders' webs, or rather raw cotton. It was of a very clammy quality, sticking fast to every thing that touched it, and capable of being spun into long threads. At first I suspected it to be the product of spiders, but could find none. Nothing was to be seen connected with it, but many brown oval husky shells, which by no means looked like insects, but rather resembled bits of the dry bark of the vine. had a plentiful crop of grapes set, when this pest appeared upon it; but the fruit was manifestly injured by this foul encumbrance. It remained all the summer, still increasing, and loaded the woody and bearing branches to a vast degree. I often pulled off great quantities by handfuls; but it was so slimy and tenacious that it could by no means be cleared. The grapes never filled to their natural perfection, but turned watery and vapid. Upon perusing the works afterwards of M. de Reaumur, I found this matter perfectly described and accounted for. Those husky shells which I had observed, were no other than the female coccus, from whose sides this cotton-like substance exudes, and serves as a covering and security for their eggs."

To this account I think proper to add, that, though the female cocci are stationary, and seldom remove from the place to which they stick, yet the male is a winged insect; and that the black dust which I saw was undoubtedly the excrement of the females, which is eaten by ants as well as flies. Though the utmost severity of our winter did not destroy these insects,

yet the attention of the gardener, in a summer or two, has entirely relieved my vine from this filthy annoyance.

As we have remarked above, that insects are often conveyed from one country to another in a very unaccountable manner, I shall here mention an emigration of small aphides, which was observed in the village of Selborne, no longer ago than August the 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 street 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.†

LETTER XCVIII.

TO THE HON. DAINES BARRINGTON.

DEAR SIR,When I happen to visit a family where gold and silver fishes are kept in a glass bowl, I am always pleased

*There are several species of these troublesome, although minute, animals; the loftiest tree is as liable to their attacks as the most humble plant. Their numbers are incalculably great. They prefer the young and tender shoots, and frequently insinuate themselves into the very heart of the plants, where they commit much havoc. Some feed indiscriminately on every kind of plant, while others confine their ravages to one species of plant only. The aphis of the rose tree too frequently despoil this delightful flower. The aphides afford a very striking deviation from the general laws of nature, one impregnation of the female is sufficient for nine generations.-ED.

+ For various methods by which several insects shift their quarters, see Derham's Physico-Theology.

The gold and silver fishes are but one species, the cyprinus auratus of Linnæus. The young fry, when first produced, are perfectly black, but they afterwards change to white, and then to gold colour; the latter colours appear first about the tail, and extend upwards. The smallest fish are the most beautiful, being of a fine orange red, appearing as if sprinkled over with gold dust: some are silvery white, and others white,

with the occurrence, because it offers me an opportunity of observing the actions and propensities of those beings with whom we can be little acquainted in their natural state. Not long since, I spent a fortnight at the house of a friend, where there was such a vivary, to which I paid no small attention, taking every occasion to remark what passed within its narrow limits. It was here that I first observed the manner in which fishes die. As soon as the creature sickens, the head sinks lower and lower, and it stands, as it were, on its head; till, getting weaker, and losing all poise, the tail turns over, and, at last, it floats on the surface of the water, with its belly uppermost. The reason why fishes, when dead, swim in that manner, is very obvious; because, when the body is no longer balanced by the fins of the belly, the broad muscular back preponderates by its own gravity, and turns the belly uppermost, as lighter, from its being a cavity, and because it contains the swimming bladders, which contribute to render it buoyant. Some that delight in gold and silver fishes, have adopted a notion that they need no aliment. True it is, that they will subsist for a long time without any apparent food but what they can collect from pure water frequently changed; yet they must draw some support from animalcula, and other nourishment, supplied by the water; because, though they seem to eat nothing, yet the consequences of eating often drop from them. That they are best pleased with such jejune diet may easily be confuted, since, if you toss them crumbs, they will seize them with great readiness, not to say greediness: however, bread should be given sparingly, lest, turning sour, it corrupt the water. They will also feed on the water plant called lemna, (duck's meat,) and also on small fry.

When they want to move a little, they gently protrude themselves with their pinna pectorales; but it is with their strong muscular tails only that they, and all fishes, shoot along with such inconceivable rapidity. It has been said, that the eyes of fishes are immoveable; but these apparently turn them forward or backward, in their sockets, as their occasions require. They take little notice of a lighted candle, though applied close to their heads, but flounce, and seem much frightened by a sudden stroke of the hand against the support whereon the bowl is hung; especially when they have been

spotted with red. When kept in ponds, they are frequently taught to rise to the surface of the water, at the sound of a bell, to be fed. They are said to have been first introduced into England in 1691.—ED.