DURING hot, midsummer days, the air above fields and ponds becomes the stage for some of the most amazing fliers in insectdom—the dragonflies.

With their two pairs of long wings glistening in the sun, you can see dragonflies flashing back and forth, looping, turning and diving at will. One moment they will be zooming at express-train speed high in the sky, then, the next, swooping down to skim the surface of a pond. These marvels of creation can even fly backward or hover in midair like a helicopter.

But the sun-loving dragonflies do not fly simply for the enjoyment of it. These aerial dynamos ply their skills to feed an insatiable appetite. In fact, Mr. Dragonfly can eat his own weight in half an hour and still be hungry.

When hunting a meal to appease their appetite, dragonflies exhibit distinctive habits. Some species search over large areas. Others have set paths that they follow generation after generation. Larger dragonflies stake out territories for themselves and drive off other dragonflies by wildly clattering their wings. Sometimes if an invading dragonfly is bold and is not intimidated by the clattering, it will be met head to head. Hovering together menacingly, these two will stay in that position while rising straight up into the sky.

Whether they take to roaming or settling in one spot, dragonflies stay alert for their favorite diet: mosquitoes and gnats. They also find tasty meals in moths and horseflies. Because of their long, slender, needle-shaped body, many persons have believed that dragonflies sting, but this they do not do. They are not only harmless to man but also very beneficial because of their devouring mammoth quantities of flies and mosquitoes.

When a dragonfly zeros in on these insects, they are completely outmatched. Equipped with six spine-fringed legs that are bunched together like a basket, dragonflies scoop prey out of the air and suck their bodies dry while racing after another victim. So swiftly do they gobble up prey that dragonflies have been known to eat forty horseflies in two hours. One dragonfly was found with its mouth gorged with one hundred mosquitoes! No wonder these voracious insects have earned the name “flying dragons.”

Mating, and Life Underwater

But there is a time when dragonflies pay less attention to eating and more to their airmanship. This is during the mating season. Rival males, seeking the attentions of a female, take to the air to do battle. Their aerial duels feature some of the most brilliant air maneuvers of any living creature. Some species are more moderate, though, and perform a sort of courtship dance.

Once they have found a mate, the males literally carry off the female. To mate, dragonflies fly in tandem, that is, the male holding the female by the back of the head while flying through the air. As the female is to mate, she extends the tip of her abdomen to the male’s second thoracic segment and receives a sperm capsule.

After her eggs are fertilized, the female deposits them on a pond’s surface or in aquatic weeds. Exactly how many eggs a dragonfly lays is open to question; but there have been found as many as 110,000 eggs in a single cluster.

The eggs lie in the water or weeds a few days. Then the offspring begin to emerge. And strange creatures they are. Other than being born with hefty appetites, these creatures, called nymphs, resemble the parents very little. They have gills in the thin walls of their intestines. These gills not only absorb oxygen, but, in times of trouble, give the nymph quick getaway power. When alarmed, the nymph just lifts its legs off the bottom of the pond, expels a jet of water through the gills, and rockets forward several inches.

Perhaps the most unusual feature of the nymph is its manner of catching food. Unlike its fleet parents, the nymph is sluggish. So it waits for a mosquito larva or minnow to swim close by. Then, suddenly, it shoots out an underlip hidden beneath the head. Sharp claws at the tip of the underlip grasp the unwary prey and pull it to the nymph’s mouth. This underlip, which is hinged and elongated, operates similarly to the human arm. The middle hinge is like the elbow, allowing the underlip to swing back and forth easily.

When the underlip is not in use and is folded back under the body, an unusual thing happens. The claws cover the nymph’s face like a bandit’s mask. An appropriate costume for these tiny submarine creatures!

Life in the Sky

Many nymphs among the nearly 5,000 species of dragonflies complete their underwater life in one year. Others, however, may take from two to five years. During this time they pass ten to fifteen successive stages of molting. Many changes take place: the number of six-sided lenses in the compound eyes increase; the antennae gain new joints; the legs lose their hairiness; the wing pads appear on the thorax. But these changes are merely a prelude to their transformation as adult dragonflies.

The nymph’s final step to being a creature of the air usually begins at night. It climbs out of the water and clings to the bank or to a stem. Twelve hooks, two on each foot, secure its hold. Here it remains motionless for some time as the body completes the metamorphosis.

Finally a rent appears on the back side of the thorax and the disheveled dragonfly struggles out of the nymphal shell. At first its four wings are damp and folded back like a fan, but steadily they are pushed open by blood swelling the vast network of veins running through the transparent tissues.

Also the colors of the newly emerged dragonfly are faint. But they intensify until the dragonfly rivals even the butterfly and moth in beauty. Its colors range the spectrum of the rainbow—brown, lavender, ultramarine, green, azure blue, scarlet, crimson, lilac, cerulean blue, red and ivory white.

The dragonfly will wait about five hours after leaving its armor-like shell to allow its wings and body to harden. Once the wings are able to carry it in flight, the dragonfly darts into the air. Never again will it use its legs to walk. It has become a creature of the air.

Powerful Flier

The largest dragonfly today is a tropical species having a wingspan of seven and a half inches. It ranks as one of insectdom’s best and strongest fliers. In fact, this most accomplished insect aviator has been known to fly fifty to sixty miles an hour!

The power for the wings is supplied by motor muscles that comprise one quarter of the dragonfly’s entire weight. These muscles, vibrating the wings 1,600 times a minute, enable dragonflies to cover huge distances. Such powerful fliers are they that ship passengers have observed them winging their way over the ocean 175 miles off the coast of Africa. One species settled on an island that lay 200 miles across open sea!

They fly the greatest distances when drought or food shortage drives them into migrating. These migrations sometimes attain fantastic proportions. In 1839 millions of them blanketed the skies as they followed rivers and streams over most of Europe. In the United States, swarms of them migrated to the South in 1881, literally darkening the skies.

But these great fliers must be ever watchful. They are in constant danger from birds, frogs and fish. Against such predators dragonflies have speed and keen sight. Their bulging eyes, which cover the better part of the head, can scan far into the distance. The Creator designed them in such a way that each eye contains as many lenses as the eyes of 15,000 men! They can also see in virtually every direction at the same time. And they are farsighted, allowing them to spot a mosquito thirty feet away.

With such vision dragonflies can dodge almost any pursuer, including man. Trying to catch these dexterous fliers can be quite a task. But Japanese children have discarded the net in favor of ingenuity. They attach tiny pebbles to the ends of long hairs and throw them into the air where dragonflies are circling. When one of the insects pounces upon the passing stone, the hair twists about its body and the weight of the pebble grounds it.

Even though these zestful creatures are able to elude most enemies, those in the temperate zone eventually get caught by the chilling winds of autumn. Life for the dragonfly is short, lasting only the warm months of spring and summer. In the fall you will find them clinging motionless to stems or leaves, numb from the cold. Flying is done only during the warmest part of the day. The first frost brings down the curtain for them, leaving the air above the fields and streams devoid of their fascinating presence.

But the chain of life does not stop. Nymphs, protected beneath the ponds and streams, continue to mature. With the hot weather, they will emerge to become a new generation of the dragons of the sky.

HAVE you noticed the marvelous sense of timing of living things? Each year plants germinate, grow and flower according to schedule. Not all are on the same schedule—some flower in the spring, others in the summer and still others in autumn and early winter. But each species knows the right time to carry out its various activities.

It is similar with animals. They breed, reproduce, become dormant, migrate and perform other functions as if they were following a precise timetable. Consider the insects that spend winter in a dormant state called diapause. Toward the end of summer, while the weather is still warm, they interrupt their busy feeding and reproduction activities and begin to settle into their dormant state. How do they know that winter is near?

Also, there are the birds that migrate to the tropics to spend the winter. With the coming of spring in the north, they head for home. Since the temperature in the tropics is about the same as when the birds arrived, how do they know that it is warming up back home? Many people have asked questions like these. Have you?

The Wondrous Timing Device

It is believed that the main timing device of living things is light. It used to be commonly thought that the changing temperatures of the season triggered the various responses in plants and animals. But temperature is variable; it is inconsistent from year to year. Light, on the other hand, is reliable. On any given day of the year the length of daylight will be the same. It never varies. Thus a living organism is provided with exact information on the advance of the seasons.

This is not to say that temperature or other factors may not also affect the seasonal rhythm of plants and animals. They apparently do. But the main timing device seems to be the length of daylight. That the activities of living things are scheduled by means of this wondrous clock is a relatively recent discovery.

An Important Investigation

In 1920 investigators were studying a certain variety of tobacco called Maryland Mammoth. They were trying to determine why it was late in flowering when grown near Washington, D.C. Although the plant was ready to flower for days, something prevented it from doing so until too late in the season for its seeds to mature.

Many experiments were conducted, but they failed to reveal the reason for the delayed flowering. Finally plants kept in a greenhouse were artificially given a shortened daily exposure of light. This did it! The plants bloomed earlier than those that were grown outside. This gave the clue as to why the Maryland Mammoth will not bloom until late in the season near Washington, D.C. It is because not until late summer has the daylight decreased to the proper length for this plant to flower!

Does light similarly affect the functions of other plants? Further research by these investigators showed that it does. It was discovered that plants can be divided into three groups, depending on their reaction to length of daylight.

First, there is the group that includes plants, such as tomatoes and cucumbers, that are not choosy as to the length of day. A second group are called “short-day” plants. These will not flower until the daily dose of light is below a certain number of hours. The third group are called “long-day” plants. These flower when daylight extends beyond a certain number of hours.

Consequence of Findings

These investigations answered many questions. They explain why plants of a given species can be planted at different times of the year, and yet all flower at the same time. And they reveal why certain plants bloom in particular districts, but will not flower at all in others.

Agriculturists now routinely determine the light requirements of plants. Some of them have very specific length-of-daylight needs. For example, various varieties of onions and soybeans do best only when grown within a belt of latitude of 150 miles. If they are grown either north or south of this region they may fail as a crop.

The daylight needs of plants can result in disappointment to flower lovers. While on a trip a person may obtain a colorful plant for his garden, but back home it may not bloom. Why? The daylight where he lives may not be of suitable length for the plant to flower.

For example, there is the rock-garden plant Sedum telephium, which grows in southern Vermont. But it needs a daily dose of sixteen hours or more of light in order to bloom. It receives this in Vermont. However, if one took it very far south it would fail to bloom because of insufficient daylight.

On the other hand, a person in northern Maine may be grateful that there is little or no ragweed there. Ragweed will not flower until daylight decreases to fourteen and a half hours. This does not occur in northern Maine until after August 1, so it does not allow enough time for seeds to mature before cold weather comes.

How Plants Detect Light

Learning these facts about the responses of plants to length of daylight made something else apparent. Plants must have something within them that detects the change in length of daylight and that causes them to respond accordingly. Just recently this substance, called “phytochrome,” has been isolated.

Phytochrome is a bluish, light-sensitive pigment that absorbs red light. It has been shown that many plants, when exposed to the red wavelength of light, mature more rapidly. Somehow the light acts on the phytochrome to regulate a plant’s growth changes, from seed stage to maturity. But it is not understood just how this is accomplished.

Manipulating the Light

Many gardeners now use to good advantage this knowledge about the responses of plants to light. By adjusting the length of exposure to light they can make a plant bloom when they want it to. Thus in winter they enjoy flowers that normally grow only in summer, and those that normally bloom in autumn they may have in other seasons.

A chrysanthemum, for instance, is normally an autumn-flowering plant. But it can be made to bloom in summer. Just cover it with a cardboard carton in the late afternoons, and remove the carton in the morning. The extended period of darkness will cause the chrysanthemums to react as if it were autumn, and they will bloom with the summer flowers.

On the other hand, a person may want to enjoy in winter flowers that normally bloom only in summer. By giving them daily doses of artificial light after the day has ended, these plants can be made to react as if the long summer days had arrived. Thus they will bloom during the short days of winter.

Effect upon Animals

After discovering the remarkable effects of the length of daylight upon plants, research was done to ascertain whether animals were similarly affected. As a result, many animals, too, were found to time their seasonal routines by the length of daylight.

The first bird experiments were conducted on starlings. Normally starlings mate in spring, when the days grow longer. However, the short days of December were lengthened artificially by turning lights on the birds after the sun went down. In a few days the starlings began to molt and take on the colorful plumage of their springtime mating season. Their breeding schedule was advanced four months by increasing the length of their daily exposure to light!

Similar experiments were conducted on ferrets, which also normally breed in spring or early summer. These small animals, too, mated in winter when they were exposed to extra periods of light. Both starlings and ferrets are long-day creatures. They are among those creatures that respond sexually to long periods of light.

However, many other animals, such as goats, sheep and deer, breed in the autumn. The shorter length of daylight affects them sexually. Thus sheep breeders, who want early spring lambs, limit their animals’ exposure to daylight late in the summer. By bringing the sheep into dark sheds toward the end of day in July and August, the reproduction process is started earlier.

Many interesting experiments have also been conducted on insects, including the silkworm. The eggs, laid in the fall, pass the winter in a dormant state. They hatch into larvae, or worms, in spring. The larvae soon change into pupae, and then into adult moths. But eggs laid in early summer do not pass through a period of dormancy.

Experiments reveal that it is the length of daylight that determines why eggs laid in early summer do not go into a state of dormancy while those laid in the fall do. By artificial regulation of the light, silkworm moths can be made to reproduce generation after generation without any of their eggs entering a stage of dormancy. But when the length of light exposure is changed, moths lay eggs that become dormant.

As with plants, there obviously is some mechanism within animals that triggers their various responses to length of light. It is believed that a hormone is involved. But few details are known as to how the light-length messages are received or transmitted.

Although man has learned much about the many marvels of creation, he is continually reminded of how much remains a mystery to him. The study of light’s effects on living things again illustrates this.

An eclipse is simply the hiding of a celestial body by the interposition of another. It can be total or partial. It is total when the hidden body is completely covered. When a part of it is covered it is annular (ring shaped) or partial. A solar eclipse is produced when the moon, in its orbit, goes between the sun and the earth, projecting its shadow on the earth below. An annular eclipse occurs when the moon is exactly in front of the sun but it is not big enough, due to its distance and position, to cover the sun completely. It leaves a ring of the sun visible. There are never annular eclipses of the moon, because the earth’s cone of shadow is always large enough to cover the moon when it is in an exactly straight line with the sun and the earth.

Eclipses are natural happenings that occur with exact regularity. They do not represent a threat nor do they carry some prediction of calamity. They are evidence of the unchangeable laws that govern the universe. They testify to the infinite divine wisdom that established each heavenly body in the universe and that controls them. Yes, they underscore how small we are when compared to the gigantic universe around us.

Yes, eclipses are marvels of Jehovah’s creation, one more evidence that assures us that the universe continues functioning according to the perfect laws he has fixed.