Part 12

The June bug, the beetle which dashes into rooms, blindly charging lights of all kinds, is a familiar example. Its larva is white and very destructive. On my lawn in California the Bermuda grass often turns white, and sections a foot square can be lifted, having been cut off from the roots by this destructive larva of the June bug, which during this stage of its existence lives underground, eating roots and plants of various kinds. For two years this beetle (Fig. 203) lives a subterranean, marauding life, growing and shedding its skin. It is often considered a complete animal, but at the end of this period it changes into what is called the pupa stage, which does not move; the pupæ are white, soft, helpless creatures which are found around the roots of rose bushes in great number, and which are so appreciated by mocking birds that they and the blackbirds invariably follow me about the garden when I am overturning the soil with the trowel. Finally the pupa changes into the perfect insect.

The larvæ of some of the spring beetles remain in the "grub" stage five years, and are known as wire worms, doing a vast amount of damage.

The girdler beetle bores holes in tender limbs of the hickory, then systematically girdles the limb below the eggs, so that by the time the young hatch they have soft, dead wood to feed upon. The bark borer (Fig. 204) penetrates the bark of trees, and cuts winding tunnels here and there, in which are placed its eggs. Among the most attractive of the beetles are the carnivorous sexton beetles. They find dead bodies with all the skill of a vulture, burrow beneath them and deposit their eggs within the body, where the young feed. The work these beetles accomplish in destroying animals and even burying them renders them valuable scavengers. Among the destructive beetles are the buffalo bugs (Fig. 205), which have been introduced from Europe; the larva of these is a strange, fuzzy little creature (a).

The weevils (Fig. 206) are the bane of the dweller in the tropics. They infest bread, cake, and flour and meal of every kind. Perhaps the most dreaded by the Northern farmer is the potato bug (Fig. 207), which plays havoc with potatoes, often ruining the entire crop, the vines being covered by the soft and disagreeable larva, more like a worm than anything else. The diving beetle is an interesting insect, being a flier and a swimmer. Its hind legs are fringed and adapted for swimming. On the fore limb is a sucker, or several, by which the beetle can attach itself to any object. The larva is a ferocious creature, armed with a pair of fierce jaws, with which it attacks small fishes, frogs, tadpoles, and game very much larger than itself.

XXV. THE BUGS

The bugs are easily recognized. They have the mouth parts arranged as a sucking beak or proboscis. The chinch bug (Fig. 208), the squash bug (Fig. 209), the seventeen-year cicada, or locust (Fig. 210), and the bean aphis (Fig. 211) are well-known examples. They represent a group dreaded for many reasons; many are parasites on man and beast, while many others destroy crops of various kinds.

In nearly all fresh-water ponds and pools curious flat, long-legged creatures (Fig. 212) are seen darting over the surface, being perfectly at home. They are water boatmen, and one species (Fig. 213) is found far out at sea.

In passing in review the various insects the peculiar transformations through which they pass are noticed; some long, some short, some partial, and many complete. In the cicada, or seventeen-year locust, or harvest fly, we have an instance of one of the strangest examples of slow development known. The cicada is a wedge-shaped insect having some resemblance to a huge fly. At the base of the abdomen is a drumlike organ by which it makes a shrill "zeeing" sound which, when thousands are joined in concert, produces a remarkable sound audible for a long distance. I have heard it half a mile with the wind, and by following it up found a grove filled with insects producing a roar of sounds, while, clinging to the trees and branches, were thousands of empty skins from which the cicadas had escaped. The cicada deposits three or four hundred eggs in holes on the twigs or bark of the oak. They hatch very promptly in six weeks or so, and we might conclude that the young cicadas would soon appear. But seventeen long years of life underground are now required before the pupa crawls upward, molts, and appears as an adult cicada. It has spent all these years as an almost helpless creature, resembling the mole cricket, subsisting by sucking the juices from the roots of plants, waiting for the ending of its imprisonment.

On many plants the stroller through the garden will observe bits of white froth, like soap suds, and few persons, were they not in the secret, would believe that the froth is an especially devised medium for the little leaf hopper (Fig. 214). The adult insect is a curious little creature found among the grasses in spring. The young require moisture to enable them to attain their full development, and when hatched they climb up stalks of grass and pierce them with their beaklike proboscis and gorge themselves with the juices. The insect now exudes a foamy secretion which bubbles up about it, in time entirely surrounding itself in a mass of moisture. The insect converts this into air globules by pushing its tail above the mass (a) and seizing air in its claspers, which it passes beneath it to the spiracle or breathing pore. In this way it breathes and also fills the section about it with air. There the animal passes the time until it is ready to change, when it escapes and becomes a perfect leaf hopper. The famous cochineal insects (Fig. 215) belong to this group. They are minute creatures which live upon certain cacti in the tropics. When collected they form the celebrated dye. Another form produces a valuable wax.

Who has not found his rose bushes swarming with minute green bodies, the Aphidæ? Brush them off at night and in a few hours as many more are seen, due to the marvelous rapidity of their increase. The eggs are laid in the autumn, and hatch in the early spring, the young then appearing as wingless little creatures which in turn produce not eggs but winged or wingless Aphidæ (Fig. 216). These appear in such numbers and so quickly that in a single summer a pair of plant lice will produce one quintillion of young ones. Can we wonder that it is difficult to keep the rose bushes free from such a swarm? The story of the development of these insects is but merely touched upon, but it is among the most remarkable of all the strange and unexplainable transformations we find in animal life.

Here we may glance at the countless scaly insects which infest fruit of various kinds. The black, red, and cottony scale are common in California, and have to be fought with all the cunning and intelligence that man can invoke. In 1886 the orange groves of southern California were almost ruined by the cottony scale. I have seen trees that looked as though the limbs were covered with snow. But an enemy of the scale, a little spotted lady bug, was imported from Australia, and in a few months the scale had disappeared. The black and red scale and several others are pests which devastate the groves, stopping the growth of the trees and operating against the fruit grower, who is obliged to spray the trees with poisonous washes to destroy them.

XXVI. FLIES AND MOSQUITOES

The flies and mosquitoes are among the greatest pests and dangers to man. Both are conveyers of disease, and the former, as an agent of destruction, deposits its eggs in meat of all kinds, making it impossible to keep meat in some countries. On the other hand, it should be remembered that the flies are valuable scavengers, hastening the destruction of dead matter which might contaminate the air.

The flies (Fig. 217) are two-winged insects with mouth parts adapted for lapping (Fig. 218) or sucking. Under the microscope these organs often appear to be composed of needlelike bristles, forming a proboscis protected by a scabbard or sheath. In some flies this weapon is many times as long as the body. The head is well separated from the body, and movable. The eyes are compound and simple, made up of many facets (Fig 219). The wings are gauze-like, often beautiful, and when the fly is in motion, they move in a figure eight, making, it is estimated, 19,800 revolutions a minute. The feet (Fig. 220) enable it to cling to the smoothest surfaces with ease. The little pads are extremely irritating at times when the fly walks over the flesh, tapping here and there with its soft tongue, in which all parts except the labium are rudimentary. The latter has a broad tip for licking or lapping. The flies breathe by spiracles, and are among the most active of all insects, and the bravest, attacking man and beast, and refusing to be driven off, despite the most active and spirited defense.

The development of the house fly is a familiar process. The eggs of the flesh fly, as an example (Fig. 221), are small, white objects which hatch into maggots. These change gradually, finally becoming pupæ, then assuming the adult form. The bluebottle fly (Fig. 222) is one of the best known. The house fly is found in greatest numbers near stables, as there, in the piles of refuse, the eggs are deposited, hatching in twenty-four hours. The young appear as fleshy, soft, footless worms or maggots, which are ravenous, and live upon the most fœtid matter for two weeks, when they change into a pupa, a barrel-shaped, cocoonlike form. For two weeks this remains motionless, when out of it breaks the perfect house fly, soon to deposit its eggs and help to produce the tens of millions of flies which swarm wherever human beings are found.

Among the many species of flies some are bloodsuckers, as the horse flies. The robber flies are the hawks of the race, carrying off other insects, even large dragon flies. The many species of horse flies attack horses and cattle, and the animals are often driven to a frenzy by their approach. An entire herd will recognize the approach of these insects and stampede. Many of the flies deposit their eggs upon the hairs or nostrils of horses. Flies exist in countless varieties, from harmless creatures to some in Africa which are deadly to cattle and horses; from the ordinary fly whose larva lives in cheese to others which thrive in alcohol and wine. In California the larva of one species is found in Lake Mono, where no other animal can live. Hundreds of bushels of them are sometimes washed upon the beaches, constituting a favorite food for the Indians.

The warfare declared against mosquitoes in America, suggested by Dr. Howard, has attracted widespread attention to these insects, which have rendered many localities absolutely uninhabitable. A Florida physician informed me that in a certain locality horses had been killed by these insatiate bloodsuckers, which are now known to be the carriers of the germs of yellow fever. Over almost every pond or pool in summer they may be seen in countless numbers, filling the air with their disagreeable music.

The proboscis, or sucking weapon, of the mosquito (Fig. 223) is an innocent-appearing object when closed; but when the sheath is open it displays a series of scimeter and sawtooth daggers (Fig. 224), which fully explains the torture of the mosquito bite or that of the gnat which crawls up one's sleeve (Fig. 225). In all these extraordinary weapons we find the same organs, the labium, labrum, and others, but with greater or less development, according to the nature of the insect.

It is the female mosquito which occasions all the trouble and renders mankind miserable in some of the otherwise most delightful resorts. On the Florida Keys I always had a mosquito bar overhead, not merely over the bed but suspended from the ceiling in midday. Even then these pests would force their way through the meshes.

The development of the mosquito is interesting (Fig. 226). The eggs are deposited as a boat-shaped mass on the surface of the water, where they drift about for several days. The larvæ appear as wigglers floating in the water, tail upward, and breathing through a tube at the tip of the abdomen which is projected above the water for the purpose. After a while the head grows larger, and several changes ensue. Then the pupa finally appears. This rises to the surface, and out bursts a full-fledged mosquito which, like a man in a canoe, balances itself while its wings dry. A few hours before it was entirely dependent upon the water and swimming in it, but now it appears to be fearful of overturning the frail craft and falling in where it would surely drown. If all goes well, it soon tries its wings and goes buzzing away. The devastation caused by the armed and bewhiskered mosquito is not generally known. Doubtless thousands have lost their lives from this unsuspected cause.

The common gnat (Fig. 227) has habits similar to those of the mosquito. They are often seen floating in the air in great swarms or bands, rising and forming as though in some mystic dance.

Closely allied to these forms are the fleas (Fig. 228), which are at once interesting and irritating. They are wingless, and have two simple eyes. The larva resembles a small caterpillar. It attains its growth in twelve days, then enters a small cocoon, which it weaves. There it remains for sixteen days, when it breaks forth a full-grown flea. Of all insects the fleas are the most amenable to instruction. Some years ago a flea circus was one of the attractions of New York, where, by looking through a magnifying glass, one could see fleas dragging chariots with other fleas dressed as cavaliers sitting on the seats. Many other seemingly impossible feats were exhibited.

XXVII. THE BUTTERFLIES AND MOTHS

Of all the insects the butterflies (Fig. 229) are the most beautiful. Nature has arrayed them in coats of many colors. Every tint and every possible shade of color, including metallic, is found among them. In some of the South American forests they are of gigantic size, a blaze of iridescent blue, as though formed of the most delicate flakes of that beautiful mineral labradorite.

The butterflies add to the beauty of nature. Among the trees they congregate, forming dashes of color, red, blue, green, and golden yellow. They vie with the flowers in their splendors; besides being ornamental they accomplish a great work in carrying pollen from flower to flower and from plant to plant. They have small heads (Fig. 230), short antennæ, and four beautiful wings which are covered with minute scales. Each of the latter when examined under a microscope becomes a resplendent object, glistening like the plate of some gorgeous armor. The mouth parts are adapted for sucking, and are coiled up when not in use (Fig. 231). They consist of two tubular or hollow threads.

The ordinary caterpillar is the larva of the butterfly. The eggs are deposited on leaves and various places, and soon hatch into caterpillars (Fig. 232). These lead a predatory life for some time, doing a vast amount of damage, almost every plant having its peculiar pest. Some affect one tree, some another. The famous elm trees of many of the New England cities have more than once been threatened by these larvæ. They shed their coats several times. The caterpillar finally merges into the chrysalis, from which it escapes as the perfect insect. All of these changes can easily be observed by keeping a caterpillar under continuous observation. The butterflies have well-developed legs, but they rarely use them for locomotion, preferring to fly from flower to flower. The tortoise-shell butterfly is a familiar form (Fig. 233), its marvelous colors resembling this shell. Some have an under covering of pure silver. Another conspicuous form is the white butterfly (Fig. 234), which, as its name suggests, is pure white, with several black spots.

When the butterfly is at rest its wings are held aloft, and many are so colored that in this position the wing resembles a leaf and the animal escapes observation. A marvelous example of this protective mimicry is observed in the East Indian butterfly, Kallima (Fig. 235). The wings have a little projection which resembles a stem from which a dark mark resembling a midrib extends. When the butterfly alights, this seeming stem, as shown in the illustration, appears to join to the branch, and the resemblance to a leaf is so perfect that the most careful observer is often deceived. Other butterflies observed by Wallace mimicked dry oak leaves and dead leaves of various kinds. All the spots and colors of decay were imitated in their wings. Other Indian forms resemble fungus, and utterly disappear as they alight upon it. No more attractive butterfly is seen than the finely marked Vanessa, the peacock butterfly (Fig. 236), which has beautiful peacock marks upon its wings in vivid blue.

In southern California, almost every spring, there is a migration of butterflies from the south northward along the Sierra Madre. I have watched them for hours, numbers being seen over a given spot every moment. By writing to postmasters and other persons in different sections, I found that the migrating band was two hundred miles long and from ten to twenty miles wide. Doubtless this was but a fraction of its actual extent, it being made up, in reality, of millions of yellow butterflies. Darwin saw such a migration in South America. Their pathway was several miles in width, they filled the air like a yellow cloud, and were several hours passing a given point. Vessels out at sea have met with similar flocks blown away from the shore.