Be this as it may, the larvae are very active little beings, twisting about with great agility, something like those of the gnat. The food of this larva is said to consist of the fleshy part of the feathers and the blood of animals, but I very much doubt this statement. I do not venture to deny that the larva will feed on these substances, when it can get them-, but, seeing that at least ninety-nine per cent, of Flea-larvae now living must have been without access to mammalian blood, or fresh feathers, this kind of food cannot be universal. Indeed, I have often wondered how Fleas support life, and, unless they feed on each other, I can scarcely understand their mode of supporting existence.

When I was at school, I had the misfortune to suffer a simultaneous dislocation and fracture of the ankle, and was conveyed to the infirmary, a large room at the top of the house. Now, this room had been without tenants ever since I remembered it, and I believe that for at least seven years no human being had entered the room, except to open the windows in the morning and shut them at night. The room was kept most scrupulously clean, and no one even imagined that a Flea was in it.

That the room was tenanted by these insects I found to my own proper cost. No sooner was the candle put out than a simultaneous attack was made on me in all directions. From every part of the room Fleas came in battalions. There was a nurse in the room, who was one of those persons that are either impervious or objectionable to Fleas, and she escaped them entirely, while they concentrated all their energies on me.

Now, a damage such as I had suffered is not conducive to rest, even with all appliances. The limb swells, until the skin feels almost unable to resist the Q Q tension, and the burning heat

is as if melted lead were being continually poured over the joint. Fever rages through the frame, and the first endeavour of the surgeon is to subdue it as much as possible. Under such circumstances, it may well be imagined that the ceaseless attacks of the Flea armies were not calculated to produce quietude, and, indeed, had the occupier of the bed been in perfect health and strength, one such night would have sufficed to drive him into a fever. The only portion of the skin that escaped was that which was covered by the bandages, and even there the dreadful little insects had found out the junctions of the bandages, forced themselves under the edges, and driven their beaks into the skin, so that when the bandage was removed in the morning, its com'se could be traced by the rows of fleabites.

The insects had never enjoyed such a chance of a banquet in their lives, and naturally made the most of it. But, I cannot but wonder on what food they had subsisted before any wretched human being was delivered over to them. Generation after generation must have been hatched, lived, and died, and never even seen a particle of blood. No animals of any kind ever remained in the room, which was entirely disused, and, as I have mentioned, only entered for a minute or two daily, and that at a time when all the Fleas were safe in their hiding-places.

The larvae are hatched about the beginning of autumn, pass the winter in the larval condition, and change to pupae in the spring of the following year. One of these pupae is shown on Woodcut LXIX. Fig. 2. When it first escapes from the larval skin it is white, but it rapidly assumes the well-kno'WTi reddish-brown hue of the perfect insect. In this state it is perfectly quiescent, the legs being enclosed in separate cases, and so remains for about a fortnight, when it throws off the pupal skin and emerges as a perfect Flea, ready to exercise its wonderful apparatus of laceration and suction, if it should only be fortunate enough to find a subject.

The Flea is possessed of an amount of muscular power which is really enormous in comparison with the size of the insect. How great is this strength is shown by the performances of the Industrious Fleas, of which we have all heard, and which some of us have seen. One of these insects will draw behind it a weight

which is as much disproportioned to the size of its body as

would be one of Pickford’s largest and heaviest-laden waggons

to a human being. With the leaping powers of the Flea we

are likewise familiar, though perhaps we have not reflected that the average jump of a Flea is about thirty times its own height, and that, supposing a man of six feet in stature were to perform the same leap, he would jump as high as the gallery of the Monument.

There are many species of Flea known to entomologists. Mr. Westwood states that the largest specimen that he has seen was captured on that curious animal, the Echidna, or Porcupine Ant-eater, of Australia. This insect measured no less than one-sixth of an inch in length, which is to most Fleas what a man of twelve feet in height would be to ordinary human beings. One of the largest Fleas that inhabit this country is that which is parasitic on the mole, and is therefore called Fulex talpce. A portrait of this odd-looking insect is given on Woodcut LXIX. Fig. 1. At Fig. a is shown the mentum or chin of the Mole Flea, with its palpus at either side, and its apparatus of lancets in the middle. The profile view of the head is given at Fig. h, so as to show these organs in a different position. One of the palpi is shown at Fig. c, as it appears when severed from the head, and the foot is drawn at Fig. d.

The Common Flea (Fulex imtans) is shown at Fig. 2 of the same illustration, and the reader can easily see how different are these two species, even in external appearance. The mentum, palpi, and lancets are shown at Fig. f.

Besides these, almost every animal has its own species of Flea, each of which has some characteristic points in which it differs from its congeners, and can be recognised with the aid of the microscope. Fortunately, in this country we have no Flea which can inflict any real damage on us. It can annoy us terribly, but there its power ceases. In the West Indies, however, there is a Flea, popularly called the Jigger, or Chigoe (^Fulex penetrans)^ which makes its way under the skin, especially of the toes, lays its eggs there, and, if it be suffered to proceed in its task unmolested, fearful ulcers come, Q Q 2

and the damage has been known to be so great that amputation has been necessary in order to preserve the life of the patient. The Chigoe, not being a British insect, must not be described in these pages ; but no history of the Flea, however short, would be complete without a reference to this small but dangerous o insect.

Diptera.

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Diptera.

CHAPTER I.

The last Order of Insects is the Dipteea, i.e. those insects whicli have only two transparent wings, incapable of being folded. In strict accuracy, these insects really have four wings, but one pair is undeveloped, and only represented by two little projections called halteres, or balancers. These will be described presently. The wings have generally at their bases a pair of little winglets, or ‘ alulets,’ which are not separate wings, but merely appendages of the true wings. The tarsi have five joints. There are other distinctions, but these are amply sufficient for our piu-poses.

Now, let us give a short time to the examination of the halteres. If the reader will take any Dipterous insect — the common Daddy-long-legs is as good an example as can be found and look at the thorax with a magnifying glass, he will see that the development of that part of the body is very curiously managed. ^ The front division, or the ‘ prothorax,’ is very small, so small indeed that it is scarcely more than a collar, just large enoiio-li to afford support to the first pair of legs. The middle divisio^ii, or ‘ mesothorax,’ is enormously large, the reason being that it has to carry not only the middle pak of legs, but the upper pair of wings, and must therefore afford space for the muscles which move those organs. And, as in the generality of the Diptera, the wings are moved with singular rapidity, it is evident that their muscles must be proportionately large The last division, or ‘metathorax,’ is larger than the prothorax, and much smaller that the mesothorax. It carries the hind pair of

legs below, and the balancers above. These organs, which are the rudiments of the under wings, are generally shaped like tiny bristles tipped with a round knob, and they are furnished with muscles by which they can be kept in a state of rapid vibration. So important are these organs that, even in those Diptera in which the upper wings are wanting, the halteres are present.

Their small size renders them useless for the purposes of flight, but it has been proved that they serve in some mode to guide the flight — how, it is not easy to say. The ordinary shape of these balancers can be seen by reference to the insect which is represented on Woodcut LXX. The word ‘ halteres ’ is Grreek, and signifles an adjunct to gymnastics, which has long been abandoned. Those athletes who competed for the -wide jump, used to take in their hands the halteres ; i.e. a pair of iron and leaden weights, and, as they made the spring, they swung the arms forward, so that the impetus of the weights should add to the force of tlieir leap. They were also employed of a larger size, for the purpose of exercising the arms, much as we use dumb-bells.

Other peculiarities of this Order of Insects will be mentioned in the course of the following pages.

With regard to the arrangement of these insects, there has been much controversy between systematic entomologists, and much yet has to be done in this respect. As, however, this is not a pui-ely systematic work, but deals more with the actions than the comparative anatomy of insects, we will accept the system of Professor Westwood, a system which he has elaborated with great labour and skill. He divides them first into two great Sections, the first of which he calls CeHhalota, because the head is quite distinct from the thorax, and not sunk into it. The larva undergoes its transformation without the body of the parent, and the claws of the tarsi are not toothed. The first of these definitions, however, is quite sufficient to enable the observer to know in Which section he ought to place any fly that may come before him.

This section he again separates into two Divisions, the first of which is the Nemocera, or Thread-horned Diptera, in which the antennal have more than .six joints, and the palpi ha\e

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