THE HOUSE FLY AND ITS ALLIES.
[Ill.u.s.tration: 84. Mouth-parts of the House fly.]
The common House fly, Musca domestica, scarcely needs an introduction to any one of our readers, and its countenance is so well known that we need not present a portrait here. But a study of the proboscis of the fly reveals a wonderful adaptability of the mouth-parts of this insect to their uses. We have already noticed the most perfect condition of these parts as seen in the horse fly. In the proboscis of the house fly the hard parts are obsolete, and instead we have a fleshy tongue like organ (Fig. 84), bent up beneath the head when at rest. The maxillae are minute, their palpi (_mp_) being single-jointed, and the mandibles (_m_) are comparatively useless, being very short and small, compared with the lancet-like jaws of the mosquito or horse fly. But the structure of the tongue itself (labium, l) is most curious. When the fly settles upon a lump of sugar or other sweet object, it unbends its tongue, extends it, and the broad k.n.o.b-like end divides into two broad, flat, muscular leaves (_l_), which thus present a sucker-like surface, with which the fly laps up liquid sweets. These two leaves are supported upon a framework of tracheal tubes. In the cut given above, Mr. Emerton has faithfully represented these modified trachae, which end in hairs projecting externally. Thus the inside of this broad fleshy expansion is rough like a rasp, and as Newport states, "is easily employed by the insect in sc.r.a.ping or tearing delicate surfaces. It is by means of this curious structure that the busy house fly occasions much mischief to the covers of our books, by sc.r.a.ping off the alb.u.minous polish, and leaving tracings of its depredations in the soiled and spotted appearance which it occasions on them. It is by means of these also that it teases us in the heat of summer, when it alights on the hand or face to sip the perspiration as it exudes from, and is condensed upon, the skin."
[Ill.u.s.tration: 85. Larva; _a_, Pupa-case of House fly.]
[Ill.u.s.tration: 86. Larva of Flesh fly.]
Every one notices that house flies are most abundant around barns in August and September, and it is in the ordure of stables that the early stages of this insect are pa.s.sed. No one has traced the transformations of this fly in our country, but we copy from Bouche"s work on the transformations of insects, the rather rude figures of the larva (Fig.
85), and pupa-case (_a_) of the Musca domestica of Europe, which is supposed to be our species. Bouche states that the larva is cylindrical, rounded posteriorly, smooth and shining, fleshy, and yellowish white, and four lines long. The pupa-case, or puparium, is dark reddish-brown, and three lines in length. It remains in the pupa state from eight to fourteen days. In Europe it is preyed upon by minute ichneumon flies (Chalcids). The flesh fly, Musca Caesar, or the Blue-bottle fly, feeds upon decaying animal matter. Its larva (Fig. 86) is long, cylindrical, the head being pointed, and the body conical, the posterior end being squarely docked. The larva of a Sargus-like form which feeds on offal, transforms into a flattened pupa-case (Fig. 87), provided with long, scattered hairs. The House fly disappears in autumn, at the approach of cold weather, though a few individuals pa.s.s through the winter, hibernating in houses, and when the rooms are heated may often be seen flying on the windows. Other species fly early in March, on warm days, having hibernated under leaves, and the bark of trees, moss, etc. An allied species, the M. vomitoria, is the Meat fly. Closely allied are the parasitic species of Tachina, which live within the bodies of caterpillars and other insects, and are among the most beneficial of insects, as they prey on thousands of injurious caterpillars. Another fly of this Muscid group, the Idia Bigoti, according to Coquerel and Mondiere, produces in the natives of Senegal, hard, red, fluctuating tumors, in which the larva resides.
[Ill.u.s.tration: 87. Larva of a Sargus-like fly.]
Many of the smaller Muscids mine leaves, running galleries within the leaf, or burrowing in seeds or under the bark of plants. We have often noticed blister-like swellings on the bark of the willow, which are occasioned by a cylindrical, short, fleshy larva (Fig. 88_a_, much enlarged), about a line in length, which changes to a pupa within the old larval skin, a.s.suming the form here represented (Fig. 88_b_), and about the last of June changes to a small black fly (Fig. 88), which Baron Osten Sacken refers doubtfully to the genus Lonchaea.
[Ill.u.s.tration: 86. Willow Blister fly.]
The Apple midge frequently does great mischief to apples after they are gathered. Mr. F. G. Sanborn states that nine-tenths of the apple crop in Wrentham, Ma.s.s., were destroyed by a fly supposed to be the Molobrus mali, or Apple midge, described by Dr. Fitch. "The eggs were supposed to have been laid in fresh apples, in the holes made by the Coddling moth (Carpocapsa pomonella), whence the larvae penetrated into all parts of the apple, working small cylindrical burrows about one-sixteenth of an inch in diameter." Mr. W. C. Fish has also sent me, from Sandwich, Ma.s.s., specimens of another kind of apple worm, which he writes has been very common in Barnstable county. "It attacks mostly the earlier varieties, seeming to have a particular fondness for the old fashioned Summer, or High-top Sweet. The larvae (Fig. 89 _a_) enter the fruit usually where it has been bored by the Apple worm (Carpocapsa), not uncommonly through the crescent-like puncture of the curculio, and sometimes through the calyx, when it has not been troubled by other insects. Many of them arrive at maturity in August, and the fly soon appears, successive generations of the maggots following until cold weather. I have frequently found the pupae in the bottom of barrels in a cellar in the winter, and the flies appear in the spring. In the early apples, the larvae work about in every direction. If there be several in an apple, they make it unfit for use. Apples that appear perfectly sound when taken from the tree, will sometimes, if kept, be all alive with them in a few weeks." Baron Osten Sacken informs me that it is a Drosophila, "the species of which live in putrescent vegetable matter, especially fruits."
[Ill.u.s.tration: 89. Apple Worm and its Larva.]
[Ill.u.s.tration: 90. Parent of the Cheese Maggot.]
[Ill.u.s.tration: 91. Pupa case of Wine-fly.]
An allied fly is the parent of the cheese maggot. The fly itself (Piophila casei, Fig. 90) is black, with metallic green reflections, and the legs are dark and paler at the knee-joints, the middle and hind pair of tarsi being dark honey yellow. The Wine fly is also a Piophila, and lives the life of a perpetual toper in old wine casks, and partially emptied beer, cider and wine bottles, where, with its pupa-case (Fig.
91), it may be found floating dead in its favorite beverage.
[Ill.u.s.tration: 92. Bird Tick.]
We now come to the more degraded forms of flies which live parasitically on various animals. We figure, from a specimen in the Museum of the Peabody Academy of Science, the Bird tick (Ornithomyia, Fig. 92), which lives upon the Great Horned Owl. Its body is much flattened, adapted for its life under the feathers, where it gorges itself with the blood of its host.
[Ill.u.s.tration: 93. The Horse Tick.]
Here belongs also the Horse tick (Hippobosca equina, Fig. 93). It is about the size of the house fly, being black, with yellow spots on the thorax. Verrill[4] says that "it attacks by preference those parts where the hair is thinnest and the skin softest, especially under the belly and between the hind legs. Its bite causes severe pain, and will irritate the gentlest horses, often rendering them almost unmanageable, and causing them to kick dangerously. When found, they cling so firmly as to be removed with some difficulty, and they are so tough as not to be readily crushed. If one escapes when captured, it will instantly return to the horse, or, perchance, to the head of its captor, where it is an undesirable guest. Another species sometimes infests the ox."
[Ill.u.s.tration: 94. Sheep Tick.]
[Ill.u.s.tration: 95. Bat Tick.]
In the wingless Sheep tick (Melophagus ovinus, Fig. 94, with the pupa-case on the left), the body is wingless and very hairy, and the proboscis is very long. The young are developed within the body of the parent, until they attain the pupa state, when she deposits the pupa case, which is nearly half as large as her abdomen. Other genera are parasitic on bats; among them are the singular spider-like Bat ticks (Nycteribia, Fig. 95), which have small bodies and enormous legs, and are either blind, or provided with four simple eyes. They are of small size, being only a line or two in length. Such degraded forms of Diptera have a remarkable resemblance to the spiders, mites, ticks, etc. The reader should compare the Nycteribia with the young six-footed moose tick figured farther on. Another spider-like fly is the Chionea valga (Fig. 96; and 97, larva of the European species), which is a degraded Tipula, The latter genus standing near the head of the Diptera. The Chionea, according to Harris, lives in its early, stages in the ground like many other gnats, and is found early in the spring, sometimes crawling over the snow. We have also figured and mentioned previously (page 41) the Bee louse, Braula, another wingless spider-like fly.
[Ill.u.s.tration: 96. Spider fly.]
[Ill.u.s.tration: 97. Larva of Spider fly.]
The Flea is also a wingless fly, and is probably, as has been suggested by an eminent entomologist, as Baron Osten Sacken informs us, a degraded genus of the family to which Mycetobia belongs. Its transformations are very unlike those of the fly ticks, and agree closely with the early stages of Mycetophila, one of the Tipulid family. In its adult condition the flea combines the characters of the Diptera, with certain features of the gra.s.shoppers and c.o.c.kroaches, and the bugs. The body of the flea (Fig. 98, greatly magnified; _a_, antennae; _b_, maxillae, and their palpi, _c_; _d_, mandibles; the latter, with the labium, which is not shown in the figure, forming the acute beak) is much compressed, and there are minute wing-pads, instead of wings, present in some species.
[Ill.u.s.tration: 98. Flea, magnified.]
[Ill.u.s.tration: 99. Larva of Flea.]
Dr. G. A. Perkins, of Salem, has succeeded in rearing in considerable numbers from the eggs, the larvae of this flea. The larvae (Fig. 99, much enlarged; _a_, antenna; _b_, the terminal segments of the abdomen), when hatched, are half a line in length. The body is long, cylindrical, and pure white, with thirteen segments exclusive of the head, and provided with rather long hairs. It is very active in its movements, and lives on blood clots, remaining on unswept floors of out-houses, or in the straw or bed of the animals they infest. In six days after the eggs are laid the larvae appear, and in a few days after leaving the egg they mature, spin a rude coc.o.o.n, and change to pupae, and the perfect insects appear in about ten days. A good authority states that the human flea does not exist in America. We never saw a specimen in this country.
A practical point is how to rid dogs of fleas. As a preventive measure, we would suggest the frequent sweeping and cleansing of the floors of their kennels, and renewing the straw or chips composing their beds,--chips being the best material for them to sleep upon. Flea afflicted dogs should be washed every few days in strong soapsuds, or weak tobacco or petroleum water.
A writer in "Science-Gossip" recommends the "use of the Persian Insect Destroyer, one package of which suffices for a good sized dog. The powder should be well rubbed in all over the skin, or the dog, if small, can be put into a bag previously dusted with the powder; in either case the dog should be washed soon after."
[Ill.u.s.tration: 100. Chique.]
One of the most serious insect torments of the tropics of America is the Sarcopsylla penetrans, called by the natives the Jigger, Chigoe, Bicho, Chique, or Pique (Fig. 100, enlarged; a, gravid female, natural size).
The female, during the dry season, bores into the feet of the natives, the operation requiring but a quarter of an hour, usually penetrating under the nails, and lives there until her body becomes distended with eggs, the hind-body swelling out to the size of a pea; her presence often causes distressing sores. The Chigoe lays about sixty eggs, depositing them in a sort of sac on each side of the external opening of the oviduct. The young develop and feed upon the swollen body of the parent flea until they mature, when they leave the body of their host and escape to the ground. The best preventive is cleanliness and the constant wearing of shoes or slippers when in the house, and of boots when out of doors.
[Ill.u.s.tration: The Willow Gall Fly.]
CHAPTER VIII.
THE BORERS OF OUR SHADE TREES.
In no way can the good taste and public spirit of our citizens be better shown than in the planting of shade trees. Regarded simply from a commercial point of view one cannot make a more paying investment than setting out an oak, elm, maple or other shade tree about his premises.
To a second generation it becomes a precious heirloom, and the planter is duly held in remembrance for those finer qualities of heart and head, and the wise forethought which prompted a deed simple and natural, but a deed too often undone. What an increased value does a fine avenue of shade trees give to real estate in a city? And in the country the single stately elm rising gracefully and benignantly over the wayside cottage, year after year like a guardian angel sending down its blessings of shade, moisture and coolness in times of drought, and shelter from the pitiless storm, recalls the tenderest a.s.sociations of generation after generation that go from the old homestead.
Occasionally the tree, or a number of them, sicken and die, or linger out a miserable existence, and we naturally after failing to ascribe the cause to bad soil, want of moisture or adverse atmospheric agencies, conclude that the tree is infested with insects, especially if the bark in certain places seems diseased. Often the disease is in streets lighted by gas, attributed to the leakage of the gas. Such a case has come up recently at Morristown, New Jersey. An elm was killed by the Elm borer (Compsidea tridentata), and the owner was on the point of suing the Gas Company for the loss of the tree from the supposed leakage of a gas pipe. While the matter was in dispute, a gentleman of that city took the pains to peel off a piece of the bark and found, as he wrote me, "great numbers of the larvae of this beetle in the bark and between the bark and the wood, while the latter is "tattooed" with sinuous grooves in every direction and the tree is completely girdled by them in some places. There are three different sizes of the larvae, evidently one, two and three years old, or more properly six, eighteen and thirty months old." The tree had to be cut down.
Dr. Harris, in his "Treatise on Injurious Insects," gives an account of the ravages of this insect, which we quote: "On the 19th of June, 1846, Theophilus Parsons, Esq., sent me some fragments of bark and insects which were taken by Mr. J. Richardson from the decaying elms on Boston Common, and among the insects I recognized a pair of these beetles in a living state. The trees were found to have suffered terribly from the ravages of these insects. Several of them had already been cut down, as past recovery; others were in a dying state, and nearly all of them were more or less affected with disease or premature decay. Their bark was perforated, to the height of thirty feet from the ground, with numerous holes, through which insects had escaped; and large pieces had become so loose, by the undermining of the grubs, as to yield to slight efforts, and come off in flakes. The inner bark was filled with burrows of the grubs, great numbers of which, in various stages of growth, together with some in the pupa state, were found therein; and even the surface of the wood, in many cases, was furrowed with their irregular tracks. Very rarely did they seem to have penetrated far into the wood itself; but their operations were mostly confined to the inner layers of the bark, which thereby became loosened from the wood beneath. The grubs rarely exceed three-quarters of an inch in length. They have no feet, and they resemble the larvae of other species of Saperda, except in being rather more flattened. They appear to complete their transformations in the third year of their existence.
"The beetles probably leave their holes in the bark during the month of June and in the beginning of July, for, in the course of thirty years, I have repeatedly taken them at various dates, from the fifth of June to the tenth of July. It is evident, from the nature and extent of their depredations, that these insects have alarmingly hastened the decay of the elm trees on Boston Mall and Common, and that they now threaten their entire destruction. Other causes, however, have probably contributed to the same end. It will be remembered that these trees have greatly suffered, in past times, from the ravages of canker-worms.
Moreover, the impenetrable state of the surface soil, the exhausted condition of the subsoil, and the deprivation of all benefit from the decomposition of acc.u.mulated leaves, which, in a state of nature, the trees would have enjoyed, but which a regard for neatness has industriously removed, have doubtless had no small influence in diminishing the vigor of the trees, and thus made them fall unresistingly a prey to insect devourers. The plan of this work precludes a more full consideration of these and other topics connected with the growth and decay of these trees; and I can only add, that it may be prudent to cut down and burn all that are much infested by the borers."
[Ill.u.s.tration: 101. Elm Tree Beetle.]
The Three-toothed Compsidea (Fig. 101), is a rather flat-bodied, dark brown beetle, with a rusty red curved line behind the eyes, two stripes on the thorax, and a three-toothed stripe on the outer edge of each wing cover. It is about one-half an inch in length.
[Ill.u.s.tration: 102. Elm Tree Borer.]
The larva (Fig. 102) is white, subcylindrical, a little flattened, with the lateral fold of the body rather prominent; the end of the body is flattened, obtuse, and nearly as wide at the end as at the first abdominal ring. The head is one-half as wide as the prothoracic ring, being rather large. The prothoracic ring, or segment just behind the head, is transversely oblong, being twice as broad as long; there is a pale dorsal corneous transversely oblong shield, being about two-thirds as long as wide, and nearly as long as the four succeeding segments; this plate is smooth, except on the posterior half, which is rough, with the front edge irregular and not extending far down the sides. Fine hairs arise from the front edge and side of the plate, and similar hairs are scattered over the body and especially around the end. On the upper side of each segment is a transversely oblong ovate roughened area, with the front edge slightly convex, and the hinder slightly arcuate. On the under side of each segment are similar rough h.o.r.n.y plates, but arcuate in front, with the hinder edge straight.
It differs from the larva of the Linden tree borer (Saperda vest.i.ta) in the body being shorter, broader, more hairy, with the tip of the abdomen flatter and more hairy. The prothoracic segment is broader and flatter, and the rough portion of the dorsal plates is larger and less tranversely ovate. The structure of the head shows that its generic distinctness from Saperda is well founded, as the head is smaller and flatter, the clypeus being twice as large, and the labrum broad and short, while in S. vest.i.ta it is longer than broad. The mandibles are much longer and slenderer, and the antennae are much smaller than in S.
vest.i.ta.
[Ill.u.s.tration: 103. Linden Tree Beetle.]
[Ill.u.s.tration: 104. Linden Tree Borer.]