There is a rather remarkable point in the structure of the wings. On the inside of the elytra, and at their bases, is a pair of membranous plates with finely-fringed edges, something like wings, for which reason they have been called ‘ alulets,’ or little wings. These cannot be seen while the insect is at rest.

but when it takes to flight, the alulets are exposed. These JSeetles have the power of producing a sort of humming sound, some species louder than others, and it is generally thought that the sound is produced by means of the alulets.

Having now glanced at the history of the perfect Beetle, we will turn to its larval existence.

There is no possibility of evading the fact, that the larva of the Dyticus is ugly. It is very ugly. It is the crocodile of the insect world, lying unseen in its muddy bed, and darting out at any luckless insect that may pass near it. One of these larvae is shown on Plate III. Fig. 4, as it appears when seizing its prey.

When full grown, this larva is two inches in length. Its colour is yellowish-brown, sometimes one tint predominating, and sometimes the other. The reader will see how this sombreness of hue enables it to lie concealed upon the mud as it waits for prey. At the end of its body may be seen two slender appendages fringed with hairs. These appendages communicate with the breathing tubes which pervade the body, and the larva may be observed in a position resembling that which is assumed by the perfect insect, the head downwards, and the extremity of the tail just above the surface of the water, suspended and balanced by the appendages.

The mode in which this formidable creature obtains its nourishment is very remarkable. The mandibles are, as may be seen by reference to the plate, large, sharp, and curved. When submitted to a good magnifier, they are seen to be constructed on the same principle as the fangs of a poisonous serpent, a hollow groove running throughout their length. This groove is not left open, but is closed for the greater part of its length by a membrane, an aperture being left at the base. This singular structure enables the larva first to plunge its mandibles deeply into the body of its prey, and then to suck out its juices though the hollow jaws.

As is the case with the carnivorous Beetles generally, the larva soon attains its full growth, and, when the time is at hand for its change into the helpless pupal condition, it takes itself to the bank, up which it climbs, and, burrowing into the damp earth, forms for itself a sort of round cell or cocoon, within which it assumes the pupal form. Should the change

occiir in the summer, the pupa changes into a Beetle in a fortnight or a few days more, according to the warmth of the weather ; but if the larva should retire within its cell in the autumn, it remains dormant during tlie winter, and does not appear until the following spring. As is the case with darkcoloured Beetles generally, the newly-developed insect is very light in colour and soft in texture, not assuming its hard, dark coat of mail until the expiration of some days.

Tliere are altogether six British species of this genus.

We now pass on to another genus, of which nineteen species are acknowledged to inhabit England, and will take, as our example, Agahus hvpunctatus, a figure of which is given on Woodcut No. VI. Fig. 1.

It has already been mentioned that the Dyticidae inhabit equally running or still water, and that they may be found indiscriminately in rivers and ponds. Still, some species prefer the still, and others the running waters, and the latter insects are almost always of brighter colour than the former. Such is the case with the pretty little Beetle which is now before us. The head is yellow in front, and black on the crown, with two rustred spots, sometimes fused into one, and sometimes so faint as to be scarcely visible. The thorax is yellow, with the exception of two round black spots on the disc. These sometimes are fused together, like those of the head. The elytra are paleyellow, diversified with small black-brown streaks, a brighter yellow spot near the middle, and a stripe of the same colom’ down the suture, and upon the lateral margins.

Passing- over several genera we come to a Beetle which is shown on Woodcut No. VI. Fig. 2. It is called Hydroporus duodedm-pustulatus, and is selected as an example of a very large genus, containing between forty and fifty species. All the Beetles of this genus have their bodies much flattened, and the tarsi of the first and middle pairs of legs with four joints, while those of the hind pair have five joints. The two first joints of the antennae are rather longer than the others.

Tliey are all small Beetles, and the present species is perhaps the largest of its fellows, though it is, on an average, only a quarter of an inch in length. The colour of the head is dull

lighter and redder in the middle. ^ I reddisli-l)rown, has a black stripe in the middle, while a i margin of the thorax margin is widened so as to form I similar stripe on the posterior marks on the thorax. The elytra are black, 1 two black lobe-like are six spots of the same colour as the [ and on each elytron of the head, three of the spots running parallel with i middle i the suture, and the other three being placed along the margin. I Beneath, the body is yellowish.

This pretty little ' Beetle is exceedingly common in some and correspondingly rare in others. Although the spots places, differ much in size and shape, and in some specimens are even fused into each other, there is no difficulty in recognising the insect.

Our next example of the Hydradephaga is Saliplus vavie~ gatus, an insect which is shown on Woodcut No. VI. Fig. 3.

Like the last species, this is a pretty little Beetle, and exceedingly variable in its colour, so variable indeed that it has been described by the same writer under the name of at least two species. It is a very small insect, not quite one-sixth of an inch in length. Its usual colour is as follows : — The head is dark brick-red, deepening into blackish-brown on the top. The thorax is paler than the head. The elytra are rather convex, sharply pointed, deep reddish-brown in colour, and have some blackish spots near the margin. This variety is common ; but there is one which is much rarer, and in this the general hue is greyish-yellow, and the whole insect altogether lighter in colour. The brightest-coloured specimens are foimd in rather swift streams running through a gravelly soil.

There are eleven British species belonging to this genus.

On Woodcut No. VI. Fig. 4, is sho^vn another of these prettilycoloured but variable Water Beetles. Its name is Gnemidotus ccesus, and it has a vast amount of detail in its colour, in spite of its small size, which does not exceed one-sixth of an inch. The general colour of the insect is light-yellow, the head is punctated, and upon the base of the thorax is a curved, punctated impression. In order to see the markings on the elytra, or indeed to see any part of the markings properly, a good lens is required. When viewed with such assistance, the

elytra are seen to be covered with alternate stripes and dots, arranged in regular lines, of which there are two on each elytron.

This pretty little Beetle may be found in most parts of England, pools and ditches being the best localities for it. It is the only British species of its genus.

Our last example of the Dyticidse is that which stands last in the list. It is called Pelohius Hermanni, and is shown on Woodcut No. VI. Fig. 5. This is the only British specimen of its genus, wnich is very distinct from all the other Dyticidse, inasmuch as there is a distinct scutellum, and all the legs are formed for walking, the hinder legs not possessing the peculiar mode of jointing which was mentioned on page 54. The body is very convex.

The coloiu’ is rather variable, but may be summed up as follows : — The hue of the Beetle is rust-red, and there is a blackish patch round the eyes. The thorax has the front and hind margins black. The convex elytra have a blackish patch in the middle, and are longitudinally wrinkled, the wrinkles converging towards the suture at the tip of the elytra. Like the preceding insect, though not very common, it is spread tolerably evenly over the country. It has the capability of producing a squeaking sound when handled.

Having now gone through the Dyticidse, we come to the second family of the Hydradephaga — that of the Gyrinidse, or Whirligig Beetles, so called on account of the manner in which they whirl themselves about on the surface of the water.

There is not the least difficulty in determining whether or not a Water Beetle belongs to the Gyrinidse. Besides the distinctions mentioned on page 54, the peculiar antenna of a Gyrinus is shown on Woodcut No. VI. Fig./, and the hinder leg at Fig. e, both being much magnified. Besides these points, all the Gyrinidse appear to differ not only from the Dyticidse, but from Beetles generally, in having, or rather in appearing to have, four compound eyes instead of two. The real fact, however, is that, in order to suit the peculiar habits of the insects, the structure of the eye is modified.

These Beetles pass the greater part of their time on the smTace of the water, rowing themselves about with wonderful

e velocity, and always on tlie look-out for prey. If the eyes j were formed like those of the Dyticidse, the water would certainly impinge against them and render the insect incapable of seeing, hy reason of the drops of water which would he splashed over its eyes. In order to enable it to : continually see properly above the surface, it is needful that the eyes should be placed high enough to he out of reach of the water ; and to enable it to see objects in the water, it is necessary that the eyes should he submerged.

All practical entomologists are personally acquainted with this latter fact ; for they know well that if they want to see objects at the bottom of the water, the only way to do so is to lie on the bank and submerge the eyes entirely. In some parts of the world fishermen use a water-telescope for the same purpose. This is nothing more than a tube, open at one end, and having a plain glass closely fitted to the other. When used, the closed end is pushed well below the surface, and the eye applied to the open end, when it is found that objects can be seen nearly as well below as above the water.

The eyes of the Whirligig Beetles are in fact water-telescopes. Instead of being placed in two masses, one on each side of the head, each is divided by the portion of the head which carries the antennae ; so that half of the eye-cluster is well out of the water, and can see objects above the surface, while the other half is submerged, and can see objects beneath it.

The Common Whirligig, Gyrinus natator, which is shown on Plate III. Fig. 3, is very gregarious in its habits, and may generally he seen in small companies, whirling about on the surface of the water in very still and sheltered places. As they dart about, they often strike against each other ; but the shock does no harm to their hard and polished bodies, and they go on with their unceasing round as if nothing had happened. Their chief object in thus continually darting over the surface is to obtain food, which consists principally of small flies. Beetles, and other insects which fall into the water. They use their long fore legs in the capture of prey. They are watchful little Beetles, and if they fear danger they dive to the bottom, and there remain until they think that they • can return in safety to the surface.

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