Insect net

“ As the sun goes down many species move which do not stir at other times. I watch the tops of the grass, the stems of the flowers, the twigs of the trees; I disturb leaves and low-growing plants with a short switch and secure each little moth that moves, taking each out of the net in a separate pill-box, selected according to the size of the insect, as he runs up the net to escape. Transferring the full boxes to the bag I continue the process until moths cease flying or night sets in. Many species can be taken with a lamp after dark. ”

“ The foliage of all trees and shrubs should be vigorously beaten and the insects captured as they fly out. When a moth is taken, the collector will first turn the net half way round so as to close the entrance, and then, directly the insect ceases fluttering, he should carefully place one of the little boxes over it and slip on the lid. The box is then transferred to the right-hand pocket. He will soon learn to do this without in any way damaging the insect. On arrival at home, the insects should be immediately killed in the laurel bottle. ”

“ This subject of the tenacity of life in insects has lately engaged the attention of Belgian naturalist Plateau. We give his more important results. At the bottom of an open vessel holding a little over a quart of fresh water he placed a very small vessel containing the insect, and covered it with a piece of cotton netting. Terrestrial insects placed in these conditions, impelled by their specific lightness, rise to the lower surface of the net-work. The movements of their legs soon cease, they do not appear to suffer, and quickly grow torpid. ”

“ For my part, I prefer gray or green as the color for a net. White should be avoided, as experience shows that a white net will often alarm an insect when a net of darker material will not cause it to fly before the collector is ready to bring the net down over the spot where it is settled.
Collecting-Jars.—In killing insects various methods have been used. In practice the most approved method is to employ a jar charged with cyanide of potash or with carbonate of ammonia. ”

“ This type of insect gradually gave rise to the orders which now contain the largest number of species, including the beetles, moths, and flies. In many lines of this neuropteroid branch, as it is called, the larva has become adapted to a mode of life quite different from that of the adult. Many fly larvae, for example, live in rotting organic material or live as parasites within the tissues of other kinds of insects, whereas the adult flies often feed at flowers on pollen and nectar, visiting the site of the larval habitat only to lay eggs. ”

“ Most water insects are, however, not seen swimming about freely, but hide amid the various plants, mosses, etc., or in the mud at the base of the plants, and they can best be captured by dragging the net through these plants. When taken from the water the net is more or less filled with mud and parts of plants, and the water must be allowed to run out and the contents of the net spread out on a cloth or on a flat stone, if such be at hand. ”

“ When one of these miniature monsters becomes full-grown, it ceases its depredations on the aphid flocks, enters a period of quietude, and fixes the rear end of its body to a leaf by exuding a glue from the extremity of its abdomen. Then it sheds its skin, which shrinks down over the body and forms a spiny mat ad- hering to the leaf and supporting the former occupant by only the tip of the body (Fig. 132 E) . With the shedding of the skin, the insect has changed from a larva to a pupa, and after a short rime it will transform into a perfect lady-beetle like its father or mother. ”

“ Small insects have, as a rule, shorter lives than large ones; those whose larvae devour highly nutritive food generally develop more quickly than those which have to live on dry, poor, substances; life-cycles follow one another most rapidly in summer weather when temperature is high and food plentiful.
In early chapters we have already noticed the long aquatic life of the larva and nymph of a dragon-fly, relatively a large insect, and the rapid multiplication of the repeated summer broods of virgin aphids (p. 18) . ”

“ Sometimes the burrow contains nothing but the well-sinker surprised at its work: sometimes—and not rarely—the hermit will be found embracing a small subterranean fungus, entire or partly consumed. It presses it convulsively to its bosom and will not be parted from it. This is the insect's booty: its worldly wealth. Scattered crumbs inform us that we have surprised the beetle at a feast. ”

“ Others, and this is the most common mode of parasitism, attack the insect in its larva state; others, in the pupa state, and still others in the perfect, or imago state. Dr. Leidy has shown that the wood-devouring species of beetle, Passalus cornutus, and some Myriopods, or "thousand legs," are, in some cases, tenanted by myriads of microscopic plants and worms which luxuriate in the alimentary canal, while the "caterpillar-fungus" attacks sickly caterpillars, filling out their bodies, and sending out shoots into the air, so that the insect looks as if transformed into a vegetable. ”

“ Insects are enfeebled at all changes in their life, and at each successive moult, when the pupa case is broken, too weak to keep guard, they flutter and rest on the water an instant before flitting away. At this instant many are seized by the wary fish. Insects leave the water mornings and evenings, particularly the latter, rarely at midday, never during rain storms or heavy winds. It is at these times, when they are leaving the water, their imitations are used to most advantage. It is that insect floating off into a new element that the fish are watching and waiting to feed on. ”

“ The beating net can be successfully used at almost every season of the year. Even on warm days in winter time many specimens can be swept from the dead grass. So long as the dew is on the plants or in rainy weather no beating should be attempted, as the more delicate species are more or less spoiled by the moisture. After one or two minutes' sweeping the contents should be examined. Those insects which are quick to take wing or which are good runners should first receive attention; the less active can then be examined more at leisure. ”

“ One can see insects stuck on them and vainly struggling to be free, and the hairs undoubtedly prevent green-fly and other such pests from interfering with the honey of the flower. In some of these cases it has been shown that the body of the insect is actually used as food, but that is more obvious with two interesting plants which specially devote themselves to the capture of insect prey. One of these is very often kept in the Boer farmhouses near Tulbagh, in South Africa, simply to attract the flies, which are a perfect pest in those dry valleys. ”

“ These take their rise from the mud at the bottom, and, extending upwards to a distance of three or four inches, afford the larva a convenient retreat from all enemies. These insects are occasionally seen swimming laboriously through the water with a peculiar zigzag motion. When out of their burrows they have considerable difficulty in keeping beneath the surface, and may be often observed floating helplessly with their exposed portions quite dry; in fact the whole integment of the insect appears to have a peculiar power of resisting the water. ”

“ In the end the insects became, owing to this acquisition of wings, and afterwards to the establishment of a complicated metamorphosis, numerically the most successful type of life in existence, the number of species, extinct and living, mounting into the millions.
All aquatic insects are evidently the descendants of terrestrial forms, and the numberless contrivances and temporary larval organs, particularly of dipterous larvæ, are evidently adaptations to the needs of the insect during its aquatic life, and which are cast aside when the creature passes to a different medium. ”

“ A sudden dash of the air-net will usually lay any flying object at the bottom. A net for aquatic insects may be made on the same principle, but should be stout, with the meshes open enough to allow free passage of water, and the bag not quite as deep as the diameter of the hoop. ”

“ We simply give some account of the most troublesome ones drawn mainly from Harris’ Insects Injurious to Vegetation.
Green-Fly, or Plant-Louse.—Aphis Rosæ.—This very common insect is a scourge to roses, from the facility of its [Pg 142] reproduction, and its numerous progeny sometimes entirely cover the leaves, the young sprouts, and the flower buds. Devouring the sap, they are very injurious, and, when numerous, sometimes destroy the plant, while they soil every part on which they collect. The most common species is of a pale green, but there is a variety of a dingy yellow. ”

“ I have often kept specimens of these larvæ in vessels of water and noticed their predaceous habits; they feed on the larvæ of other water insects, but are not able to destroy fish, not being furnished with jaws or bodies nearly so strong as the perfect insect itself possesses. When the larva wishes to turn into its pupa state, it makes a round hole in the bank of the pond it inhabits, and there undergoes its change, turning into a full-grown beetle in about three [Pg 31] weeks' time. ”

“ The price, then, of a good collection is eternal vigilance. Most insects, when exposed for any length of time to strong light, fade or lose color, and the only way to prevent such achromatism is to exclude the light.
Insect pests affecting collections include Psocidæ, Mites, Tineidæ, Coleoptera of the families Ptinidæ and Dermestidæ, these last being the most injurious. ”

“ To be successful, the net must be swung swiftly. Insects have many eyes and are very wide awake and have no desire to be caught; therefore, the collector must be very active if he gets anything. One method of using the net is called "sweeping;" to do this take the handle about a foot and a half above the ring and pass the net quickly back and forth striking it against the grass in front of you as you walk through open fields; the net must be turned at each stroke and kept in rapid motion or the insects will escape. ”

“ In this process the entire old skin is shed, an operation well worth seeing. Under the old coat a new one has formed, which being larger, accommodates itself to the insect's increased size. The larval stage is in the case of many insects the active time when, if they are vegetable feeders, they injure crops.
When the larva has completed its growth it changes into a pupa. Some insects pass this third stage inside of silken cases they spin about themselves, others, after shedding the larval skin, find themselves each clad in a sort of horny coat of mail. We call these chrysalides. ”

“ In hot countries the great business of removing corrupt animal matter, which the vulture and hyæna imperfectly perform, is effected with certainty and speed by the myriads of insects that spring from the eggs deposited in every carcase by some fly seeking therein the means of life for her progeny. Destruction and reproduction, the great laws of nature, are carried on very greatly through the instrumentality of insects; and the same principle regulates even the increase of particular species of insects themselves. ”

“ Since the roots cannot live without nourishment, the tree dies. As soon as the larvæ have completed their development they pupate. Later they develop into adult beetles. These adult beetles issue forth in swarms the following spring, to attack new trees.
[158] The control of insect pests is a difficult matter. On areas where insect depredations are conspicuous and are liable to spread to nearby valuable timber, control measures are undertaken in coöperation with experts from the Bureau of Entomology. ”

“ Subdivision I.—LECANODIASPIDÆ, Targioni-Tozzetti.
Female insects exhibiting in all stages the abdominal cleft and lobes. Larvæ free, naked, active. Females after the first metamorphosis constructing over themselves a carapace, shield, « 64 » or (as called herein) test, of glassy, waxy, or horny secretion. Test apparently homogeneous, really in most cases formed of aggregated segments over the insect, and prolonged beyond the body in a flat single fringe of separate, more or less triangular or quadrate, segments. Fringe not always present or conspicuous in all stages. ”

“ Neuroptera proper (Hellgrammites, Lace-wings, Ant-lions, Caddis-flies, etc.) —Among the largest insects of this order are the Sialidæ, which includes the enormous Hellgrammite Fly, Corydalus cornutus. The larvæ of this insect are carnivorous and occur in streams, under stones, etc. The adults may be collected in neighboring situations and are also attracted to light. The Lace-wing flies (Chrysopa) , Ant-lions, etc., are carnivorous as larvæ, and occur, the former among the Aphides which infest various plants and the latter at the bottom of pits in loose, [60] sandy soil. ”

“ The insect world, which during the hot weather was held in such small account, now holds itself supreme. Convinced themselves that entomology is the finest study in the world, the insects carry their doctrine at their tails’ point to convince others. Every one must learn and be quite clear about the difference between a black mosquito with grey spots, and a grey mosquito with black spots. There must be no confusion between a fly which stings you if you touch it, and a fly which if it touches you stings. No one can pretend to ignore the insect invaders — the bullety beetles and maggoty ants. ”