Sawfly

“ Avenues, and long walks under hedges, and pasture-fields, and mown meadows where cattle graze, are her delight, especially if there are trees interspersed; because in such spots insects most abound. When a fly is taken a smart snap from her bill is heard, resembling the noise at the shutting of a watch- case; but the motion of the mandibles are too quick for the eye.
The swallow, probably the male bird, is the excubitor to house- martins, and other little birds, announcing the approach of birds of prey. ”

“ There is a kind of fly called the saw-fly; it has four wings, and commonly its body is yellow, and its head is black; but the most curious part of it is the saw. The young ones feed upon the leaves of rose-bushes, and gooseberries, and raspberries, and currants, and several other kinds of bushes; and the old ones always lay their eggs on the branches of these bushes, so that the young ones may have something to eat as soon as they come out. ”

“ They haunt almost every kind of tree and many plants, and one valuable plant, the Turnip, is so devastated by them, that whole crops are sometimes swept away. As, therefore, the knowledge of the life-history of any insect will tell us whether to protect or destroy it, and the best method of adopting either course, we will cast a hasty glance at some of our commonest Saw-flies, the instruments which they employ, the mode in which they use them, and the analogies between them and the saws made by the hand of man. ”

“ This insect is of a light-red colour, about the size of our largest English species, the wood-ant, but with much more powerful jaws. It does great injury to young trees, and will sometimes strip them of their leaves in a single night. We often see, hurrying across the pathways, rows of small green leaves; these are the Saübas, each with a piece of leaf cut as smoothly as with scissors, and completely hiding the body from sight. ”

“ A friend of Edward at Turriff found four Saw-flies in a piece of a fir tree that [210] was being cut up for firewood. They are called Saw-flies “from the fact that the female possesses, posteriorly, an instrument by which she perforates, or rather saws, holes in trees, into which she drops her eggs. From this it will be seen that the larvæ are woodfeeders. In this country they are by no means numerous, and it is well that they are not, or our forests would shortly disappear; for, in places where they abound, such as in Norway, they destroy hundreds of thousands of trees in a season. ”

“ Fig. 18. Young Larva (FL) , Full-grown Larva (SL) and Pupa (N) of Hive-bee (Apis mellifica) . co, cocoon; sp, spiracles; ce, eye; an, feeler; m, mandible; l, labium. Magnified 4 times. After Cheshire, Bees.
Among those saw-flies whose larvae feed throughout life in a concealed situation, we find an interesting transition between the caterpillar and the legless grub. For example, the giant saw-flies (so called 'Wood-wasps') have larvae that burrow in timber, and these larvae possess relatively large heads, somewhat flattened bodies with pointed tail-end, and very greatly reduced legs. ”

“ On plate D, fig. 7, is seen the common Hornet, one of the really terrible of our insects. It mostly makes its nest in hollow trees, and it behoves one to keep very clear of the neighbourhood. The nest is made of wood-fibre, nibbled, and made into a primitive papier-maché.
Two of the Saw-flies may be seen on plate J. Fig. 2 is the common green Saw-fly, and fig. 3 the dreaded Turnip-fly. These are called Saw-flies because they are furnished with saw-like implements, by means of which they cut grooves in certain plants, and in those grooves lay their eggs. ”

“ The swallow-tail, under its form of butterfly, is not first small, then medium, then large. When, for the first time, it opens its wings and takes flight, it is as large as it ever will be. When it comes out from under ground, where it lived as a grub, when for the first time it appears in the daylight, the June bug is such as you know it. There are little cats, but no little swallow-tails nor little June bugs. After the metamorphosis, an insect is what it will be to the end. ”

“ But he was getting a little careless. And one day, as he was sleeping, or basking, some ten feet below the surface, the broad, dark form of a sawfish arose beneath him and thrust at him with his dreadful saw. ”

“ One by one the swarm sought their original haunt, settling on the bramble, and I now noticed that only in occasional instances did the insects seek the flowers, the attraction seeming to be confined to the leaves. I stole up softly for a nearer point of observation, and could now distinctly see the beautiful yellow and black open wings of the swallow-tail softly gliding or gently fluttering as it hung from the edge of a leaf, while it explored its surface with its uncoiled capillary tongue. ”

“ Insects, reptiles, antelopes, monkeys, even man himself, must give way before the advancing hosts of the drivers; for it is certain death to stand in their path.
Saw-Flies
The saw-flies also belong to the order of the Hymenoptera. These flies are so called because the female insects have two little saws at the end of the body, which work in turns, one being pushed forward as the other is drawn back. With these they cut little grooves in the bark of twigs, or in the midribs of leaves, in which they place their eggs by means of the ovipositor between the saws. ”

“ Nature has so admirably disguised this insect in the external form of that tribe of butterflys which she intends it to represent, that it was only upon looking to its anatomical construction, that we discovered it was a type of the true Papilionæ, and not of the Erycinæ. The construction of the anterior feet, of the head and palpi, and of the antennæ, all which are here represented, magnified, places this fact beyond doubt, and leaves us nothing to desire but a knowledge of its caterpillar and chrysalis, and of the direction of the wings when the species is at rest. ”

“ In ascending this scale of being, while there is a progress upwards, the beetles, for instance, being higher than the bugs and grasshoppers; and the butterflies and moths, on the whole, being more highly organized than the flies; and while we see the hymenopterous saw-flies, with their larvæ mimicking so closely the caterpillars of the butterflies, in the progress from the saw-flies up to the bees we behold a gradual loss of the lower saw-fly characters in the Cynips and Chalcid flies, and see in [Pg 151] the sand-wasps and true wasps a constant and accelerating likeness to the bee form. ”

“ When a female saw-fly has selected the branch of a rose-tree, or any other, in which to deposit her eggs, she may be seen bending the end of her belly inwards, in form of a crescent, and protruding her saw, at the same time, to penetrate the bark or wood. ”

“ They must all be mounted—the insects quivering upon brass wire, the humming-birds with their feathers ruffled; they must be cleansed and polished, the beak in a bright red, claw repaired with a silk thread, dead eyes replaced with sparkling pearls, and the insect or the bird restored to an appearance of life and grace. ”

“ The body of the male is a little more than three-twentieths of an inch long; that of the female, one-fifth of an inch or more; and the wings expand nearly or quite two-fifths of an inch. These saw-flies come out of the ground at various times between the 20th of May and the middle of June, during which period they pair, and lay their eggs. The females do not fly much, and may be seen, during most of the day, resting on the leaves; and, when touched, they draw up their legs, and fall to the ground. ”

“ As is the case with so many of our Swallowtail butterflies, the Green-clouded Swallowtail passes through the winter in the chrysalis stage. Late in spring the butterflies emerge and soon afterward lay their eggs singly upon the leaves of sassafras or spice bush. The eggs soon hatch into lead-colored caterpillars, largely covered with spiny warts. Each caterpillar cleverly makes a protecting nest by eating out a narrow strip in the leaf which frees a flap along the margin that is turned back upon the leaf, making a case in which the larva lives. ”

“ Do you even know distinctly from each other,— (for that is the real naturalist's business; instead of confounding them with each other) ,—do you know distinctly the five great species of this familiar bird?—the swallow, the house-martin, the sand-martin, the swift, and the Alpine swift?—or can you so much as answer the first question which would suggest itself to any careful observer of the form of its most familiar species,—yet which I do not find proposed, far less answered, in any scientific book,—namely, why a swallow has a swallow-tail? ”

“ The Tenthredinidae, or true saw-flies, are distinguished by two spines on each fore-shin, while the larvae are usually caterpillars, with three pairs of thoracic legs, and from six to eight pairs of abdominal pro-legs the latter not possessing the hooks found on the pro-legs of lepidopterous caterpillars. Most saw-fly larvae devour leaves, and the beautifully serrate processes of the ovipositor are well adapted for egg-laying in plant tissues. Some saw-fly larvae are protected by a slimy secretion (fig. 6, c) and a few live concealed in galls. ”

“ Also, a fly when it settles remains quiet, whereas an aculeate if in a flower sets to work collecting pollen, or if basking in the sun on a leaf rarely rests for many seconds without moving in some way. On a flower, if an insect is seen quietly sitting with its head away from the centre of the {94}flower, it is almost certain to be a fly. ”

“ When the archer espies an insect which it wishes to seize, but which is flying too high above the surface to be captured by leaping out of the water, it approaches as near as possible to its prey, then it fills its mouth-cavity with water, shuts its gill-openings, suddenly compresses its little slit of a mouth, and, ejecting rapidly the water through the very narrow tube which forms its snout, squirts it often to the distance of two metres, and that with such force that the insect is stunned and falls into the sea. ”

“ While staying near the forest I was several times struck by the curious formation of the wings of one of the smaller species of butterfly. The insect in question is of plain inconspicuous colouring, chiefly shades of brown, and when at rest sits with the wings erect. The noticeable point is that there are several strongly marked and dark-tinted processes from the hinder part of the wings, which resemble the head, eyes and antennæ of a butterfly, so that when at rest it is very difficult to say which is the head and which is the tail of the insect. ”

“ There, perched on a fence-stake or a tall mullein stalk, he glances his eye in various directions, watching the passing insects, after which he darts with a more direct motion than in spring. Having secured one, he returns to the same or another stalk, beats the insect, and then swallows it. He frequently flies high over the large rivers and lakes, sailing and dashing about in pursuit of insects. Again, gliding down towards the water, he drinks in the manner of various species of Swallow. ”

“ These birds have a peculiar manner of flying; flitting about with odd jerks, and vacillations, not unlike the p. 42motions of a butterfly. Doubtless the flight of all hirundines is influenced by, and adapted to, the peculiar sort of insects which furnish their food. Hence it would be worth inquiry to examine what particular genus of insects affords the principal food of each respective species of swallow.
Notwithstanding what has been advanced above, some few sand-martins, I see, haunt the skirts of London, frequenting the dirty pools in Saint George’s Fields, and about Whitechapel. ”

“ One of the chief difficulties experienced by an observer who is not versed in classification is to avoid being deceived by various flies, which in many cases greatly resemble bees, and especially wasps or the wasp-like fossors. They may mostly be known by their flight, and, when they settle, by their behaviour. A fly is more sudden in its movements—those wasp-like flies, for instance, which poise themselves in the air and appear quite stationary but dart off in a second when approached, betray themselves at once by their alertness. ”

“ They are an obvious and very natural family, though the species are as yet but little understood, and not one half of them described. I have observed a singular peculiarity in a great many of these insects, which is, that when they are at rest in the sun, the lower wings are constantly in a quick vibrating motion up and down, as if the insect was rubbing them together, more particularly where the two lobes (or obtuse tails) of the under wings meet, though what purpose this is intended to accomplish remains unknown. ”

“ The insect-hawking birds are not a natural group; by descent they have nothing at all to do with one another. Closely as the swift resembles the swallow in form, in flight, in shape of bill, in habits and manners, we now know that the swift is a specialized woodpecker, while the swallow and the martins are specialized sparrows. ”

“ These insects, in fact, watch the departure of the Anthophora to endeavour to penetrate into their nests and lay their eggs there. The gallery of entry and exit has been built with grains of sand, the débris produced by the insect in working. These grains of sand glued together form, on drying, a very resistant wall.101
Fig. 35.
The other animals of which I have to speak are genuine masons, who prepare their mortar by tempering moistened earth. Every one has seen the Swallow in spring working at its nest in the corner of a window. ”