網頁圖片
PDF
ePub 版

they were covered with rime frost, and dead to appearance; but when placed in the warmth they soon began to hum. Perhaps the cause may be owing to something peculiar in the insect for local districts; for instance, it is said ihat the hornet is not found in Cambridge or Lincolnshire: the fact that they abound in Norfolk, an adjoining county, is in favour of this. There is one thing, however, much against it; that is, hornets are never so numerous as wasps; yet there are more queens reared in their nests than in those of wasps. This argues in favour of the climate and food being more against their increase. The hornet may be considered more an inhabitant of woods than the wasp ; and, as regards food, though they visit the garden and orchard in search of it, still their greatest supply is from the forest. They will unbark the young shoots of trees ; for instance, the ash : frequently the shoots appear as if they had been eaten by rabbits. This shows they have great power in their mandibles; and it is a curious fact, that, like some other insects when in confinement, in a pill-box for instance, they do not attempt to escape by cutting through it, which they could do in a few minutes.”

Hornets have been very numerous during the last season. I have assisted in destroying many of their nests, which gave me an opportunity of observing their manner of defence. If their nests had not been previously disturbed, they might be approached with safety; if otherwise, not. At first, when the attack is made, those that issue from the nest show bold resistance, yet seldom sting without giving notice of their intention, by whizzing with great force close by one's ear; but, for all their strength and courage, they sooner give way than their weaker fellows the wasps : these are waspish to the last, while the hornets that escape hum off in the distance.

Cossey Gardens, April 4. 1843.

ART. V. Some Account of the Insects which attack the Raspberry.

By J. O. Westwood, F.L.S, Secretary to the Entomological So

ciety of London. THERE are but few species of insects which materially injure the leaves or fruit of the raspberry. This plant, like most vegetables, has, of course, its aphis and its lepidopterous caterpillars which gnaw the leaves ; but the obnoxious species may be considered as consisting only of the grub of a moth which attacks the bud, and that of a beetle which attacks the fruit. Of the former, the individuals are produced in the preceding autumn, and are thus of a considerable size when the spring developes the buds, into the base of which they burrow and penetrate to the heart, consuming the embryo flowers and leaves in the same manner as I have described in my account of the caterpillar of the apricot moth. The buds thus attacked may be easily known by their faded appearance, and should be hand-picked and destroyed.

The other insect above mentioned does not commence its attacks until the fruit approaches maturity. Many of the berries may now be perceived more or less shriveled, with the seed-vessels dried up. If one of these be opened, the central core of the fruit will be found more or less burrowed, as well as the fruit, the seeds of which are left bare and dry, especially at

of

the top, the remainder not being full-sized, and generally prematurely ripe and discoloured. This is done by a whitish grub, of about a quarter of an inch long, and rather cylindric in figure; with the under side of the body and sides, and articulations of the segments, dirty white; the head and a dorsal plate on each ring brownish buff, with the sides and a central longitudinal line on each plate brown, thus giving the appearance three dorsal lines of brown. The head is

Fig. 98. The Raspberry Beetle. horny, and furnished a, Full-grown raspberry: 6, Raspberry attacked by the larva, and

not arrived at the full growth; many of the seed-cells dried up. with horny jaws and c, The same opened, to show the larva on the core, into which it short feelers, as well

burrows. d, The larva. e, The perfect insect Aying, of the as with the various membranous parts usually present, composing the under portions of the mouth of the larvæ of Coleoptera. The grub is also furnished with six short scaly articulated feet. It has also two short scaly horns on the upper side of the extremity of the body; the under side being furnished with a fleshy retractile tubercle, which the insect uses as a seventh foot. When full grown

it descends to the earth, where it buries itself to a considerable depth, forming for itself a small oval cocoon of earth, with the inner surface quite smooth. Here it assumes the ordinary pupa state to which all coleopterous insects are subject. Šome individuals which I reared did not arrive at the perfect state till the following spring, when they produced the Byturus tomentosus, a small buff or slaty brown coloured oval beetle, with knobbed antennæ, which is to be seen flying about the raspberry plants in the spring and summer, and which is also very partial to the hawthorn and blackberry.

I am the more desirous of stating the result of my own observations, because Mr. Curtis, in his account of this beetle, appears to be in some doubt whether the maggots found in the fruit of the raspberry are those of this insect; whilst Messrs.

[graphic]

natural size.

Kirby and Spence state that, when in flower, the footstalks of the blossom are occasionally eaten through by the Derméstes (Bytùrus) tomentosus, which they once saw prove fatal to a whole crop. They also add, “ that bees frequently anticipate us, and, by sucking the fruit with their proboscises, spoil it for the table." A more nauseous annoyance is, however, sometimes produced by some of the winged bugs (chiefly species of Cápsus), which protrude their rostrums into the fruit, leaving behind a taste very much like the smell of the bed-bug.

The following are the systematic details of the species in question: Order, Coleoptera (or beetles).

h Section, Pentámera (with 5.jointed tarsi).

f Family, Nitidùlidæ. Genus, Bytùrus Latreille (Derméstes Fabr.) Species, Bytùrus tomentosus Fabr. Variety, Derméstes fumatus Fabr. Synonyme, Silpha testácea ? Linnæus.

Length, about one sixth of an inch; body oval, densely clothed with luteous, yellowish, brownish, or greyish pubescence; the forehead depressed

9 and punctured; the eyes large and

Fig. 99. The Raspberry Beetle. black; the thorax punctured, as well The larva magnified. The cocoon of as the elytra ; the legs, antennæ, seen on the der side, magnífied. , Thé

perfect insect (the lines show the natuand mouth pale buffish, or ochre- ral length), magnified. coloured ; the body beneath dark brown, with the extremity lighter-coloured.

Hammersmith, Sept. 15. 1842.

[graphic]

Art. VI. Dinbur Castle, its Gardens, and its Gardeners. By PETER

MACKENZIE.

(Continued from p. 110.) When the night arrived on which Colin Forbes was to take his turn in imparting useful information to his comrades, he told them that what he intended to communicate might be thought by some to have little connexion with gardening, but he hoped, before he was done, he would be able to show that the subject was worthy of a gardener's consideration.

Hydrodynamics formed the science to which he intended to direct their attention for a short time; and he glanced in their order at the four principal parts into which it is divided, viz. Hydrostatics, which explain the laws of the equilibrium of such fluids as water; and Hydraulics, which explain the laws of their motion ; Aerostatics, which treat of the laws of the equilibrium of such fluids as air; and Pneumatics, which treat of their motion. “Before I proceed any further,” said Colin, “ I will inform you of the circumstance which first turned my attention to the subject. In the first year of my apprenticeship, whilst we were enlarging the pleasure-ground, part of the opera

3d Ser. - 1843. VIII.

E E

tions were extended into a field but poorly supplied with water. In the course of working we came upon a small spring, which the gardener thought would be of great benefit to the cattle if it were conveyed to a proper place for their use. gentleman happened to be present who held a situation under government, and whose business it was to superintend ground work. His opinion was that it would be useless to expend money upon the spring; because it appeared so weak, and the field so level

, that, when the water began to collect, its own weight would prevent the spring from running. The gardener, however, thought differently. He believed that, however weak the spring might be, it would rise to its level although it had a lake to oppose it ; and the spring, for any thing he knew, would balance an ocean; or else he had been wrongly instructed. The gentleman was not at all pleased at having his opinion controverted by one whom he considered bis inferior ; but both were willing that a temporary dam should be made in order to test their knowledge, and I watched the rising of the water from day to day until it ran over its appointed boundary. The gentleman obtained a lesson which he would perhaps remember all the days of his life, and the cattle obtained water, which was a great benefit both for them and their owner. Sometime after I fell in with part of Playfair's Outlines of Natural Philosophy, which gave me a little help on the subject. I also procured an odd number of Nicholson's Journal, containing an article entitled: A Summary of the most useful Parts of Hydraulics, chiefly extracted and abridged from Eytelwein's Handbuch der Mechanik und der Hydraulik. These short treatises gave me new views of common things.”

Colin Forbes then began to explain to the other lads the equilibrium of fluids, and taking his spirit level showed Bauldy how to use it. “He showed them that it is upon the tendency of all the particles of fluids to come to a level that the making of leveling instruments depends : and, if the person who opposed the collecting of the water had remembered that, if a communication by means of a tube or pipe, either straight or crooked, be made between the water in one vessel and that in another, the surface of both will be at the same level before the water is at rest, and if he had also remembered that the water in the spout of a teapot will balance all the water in the pot, he would never have acted as he did. If persons would accustom themselves a little more to observation and thinking, they would be less liable to fall into blunders. It is no uncommon thing for gardeners to superintend the formation of ponds and lakes in pleasure-grounds, and it is of great importance to know something about the nature and properties of the materials they have to deal with ; for accidental circumstances frequently cause much mischief, not easily repaired. He once knew a flower-garden nearly ruined by the breaking down of a small lake; gravel was washed upon the ground, and many of the shrubs removed by the force of the water. Whereas, if proper attention had been paid in the erection of the dam, the disaster would have been prevented. He then gave some illustrations of the pressure of Auids, and made them acquainted with the hydrostatic paradox. He laid down the rules for finding the pressure of water upon level and sloping surfaces, and for finding the centre of gravity, and the centre of pressure, as well as the specific gravity, of bodies in general ; and demonstrated the principle on which the siphon works, and its applica. tion to horticultural purposes. He also noticed capillary attraction, and ex. plained to them how glass in garden erections is broken by means of it in winter, when broad overlapping is practised in glazing. He informed them of some of the important offices that are supposed to be performed in nature by capillary attraction, such as the distribution of moisture in the soil, and the rise and circulation of sap in vegetables by means of their fine capillary tubes,

After having explained that part of the science which makes us acquainted with the proportion of the equilibrium and pressure of Auids, he next turned to Hydraulics, that division of “natural philosophy which treats of the motion of liquids, the laws by which they are regulated, and the effects which they produce.” He endeavoured to make them understand that important theorem, viz. “The velocity with which a liquid issues from an infinitely small orifice in the bottom or side of a vessel that is kept full, is equal to that which a heavy body would

acquire by falling from the level of the surface to the level of the orifice.” He next informed them of many things which they did not know respecting the motion of water in various channels, such as rivers, pipes, &c. ; pointed out to them the wise provision of Providence in regulating the flow of water in rivers, and preventing it from bringing destruction on the earth; and, by means of the garden-syringe and garden-engine, explained the difference between the ordinary lift-pump and forcing-pump, and the principles on which they act.

It would occupy too much of the pages of this Magazine to state all the varied and interesting information that Colin Forbes imparted that night, in the bothy, to bis attentive listeners. He tried to make his statements as plain as he could, illustrated his discourse with very simple apparatus. Some inay be deterred from the pursuit of science when they see or read about the splendid apparatus employed in the lecture rooms of wealthy institutions, but it will often be found that the same truths may be conveyed to the minds of a homely audience by means of simple things, easily got, and costing little.

It happened that Bauldy Black was cook in the bothy on the night on which Colin Forbes was to deliver his discourse. Bauldy was rather later than he should have been in preparing the supper, and, during the time he was cooking, Colin was arranging the few things he had collected in order to make his remarks better understood ; when it was agreed that he should proceed with his discourse while the supper was cooling. Finding that his remarks on Hydraulics had occupied more time than he intended, he determined on leaving the remainder for another occasion, to the great delight of Bauldy, who appeared very impatient to question him on some things. He told Colin very plainly that he could na tak in some o' the things that he heard him say." Colin asked him to mention the things he had said which he did not believe, and he would try and help him to understand them better. “ Weel,” said Bauldy, “ didna ye say that a wee drap water in a dish could be made to balance as much as if the dish had been fu o' water? I canna believe that sic a thing can happen.”—“Well, Bauldy,” said Colin, “would you like if I were to tell you that you were a poor hand at making porridge ?” -“ No, I wouldna like it, for I will tak in hand to mak parritch wi ony man in Scotland or his wife either; and nane o’yer gruel-like parritch would I mak, that might run a mile on a deal board and burn a body at the end o't ; and I'll warrant ye'll get them to yer supper this night that the skin hasna cracked in the coolin, and ye may whommil them out on yer loof and nae scaith come o'er them.” — “Well that is just what I want,” said Colin ; " for you know that when they are well made, like most other substances, they contract in cooling, and a small space is left between the sides of the basin and its contents.”- -“ That's a' true,” replied Bauldy:-“Well, if you pour a small quantity of milk into that space you will find that it floats the porridge in the basin.” — “I hae done that mony a time,” said Bauldy; " but what does that signify ?”—“That small drop of milk will press as heavily as if the basin were full of milk, and you suspended the porridge so as to have no weight on the basin.”—“Weel, weel, that will soon be tried,” said Bauldy. So away he went and got a clean piece of net, and, turning his porridge out of the basin, placed his supper in the net. According to Colin's direction he poured a few spoonfuls of milk into the basin, and placing it in one scale put weights in the opposite one. He then gently lowered the porridge in the net into the basin. The milk rose in it and brought down the opposite scale, so that it required more weight to balance it. When it was brought to balance, the height which the milk rose to in the basin was marked, and he was directed to take out the porridge, which he suspended in his hand, and let the basin remain in the scale. He was then told to pour milk into it until it would balance the weights in the other scale. He thought a small quantity would do it, and as he kept pouring he often looked at the other scale, but it showed no signs of rising until the

« 上一頁繼續 »