This edited article about insects originally appeared in Look and Learn issue number 234 published on 9 July 1966.

Huge dragonfly-like insects lived in prehistoric forests

Two questions which will probably occur to anybody who looks at insects in all their variety are: “Why are there so many of them?” and “Where did they come from?”

Study of the lives of insects gives us an idea as to why there should be so many, for every different sort does a particular job which is not done by anything else in the area in which it lives. The large numbers of different species can be accounted for by the limited abilities of each one, for there are few “Jack-of-all-trades” among insects.

To discover how insects came into being is much more difficult, for in the animal kingdom are many related creatures. Spiders and crabs, for example, both have jointed legs attached to a hard skeleton outside the body. But these are cousins, not ancestors, to the insects.

We know what the ancestors may have looked like, however, through the discovery of a “living fossil” type of animal, known from many tropical parts of the world. This is called Peripatus, or Velvet Worm, because its body is covered by a huge number of tiny bumps which look like plush.

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This edited article about the dragonfly originally appeared in Look and Learn issue number 233 published on 2 July 1966.

Various types of dragonfly

One of the largest insects in Britain today is the dragonfly. Today’s dragonflies are, however, mere dwarfs compared to some kinds which lived in the past and grew to a wingspan of as much as 30 inches.

Nonetheless, modern dragonflies are in many ways like their ancient ancestors in both shape and way of life. For example the larva, or the “nymph” as it is usually called, still does not go through a resting or pupal stage before changing to the adult state.

Another curious thing about dragonflies is that, although they all have four wings, these are not used as two pairs together, as in more recently evolved insects, but as separate pairs.

Although some of the big species can fly faster than most other insects, they beat their wings rather slowly – about 14 times per second. The rustling noise made as they fly is caused by the wings brushing against each other.

At one time, their size and the noise of their flight made people fear dragonflies. An old country name for them is “Horse-stingers”, but in fact they never attack any creature which they cannot catch in flight and carry away.

At the edge of a stream or pool in summer the small dragonfly-like insects called damsel-flies can sometimes be seen. Usually these have a rather weak flight, and when at rest they are able to fold their wings over their backs.

Dragonflies’ wings are not “hinged” in this way, but are held stiffly at the sides at all times.

Dragonflies and damsel-flies start their life in water, where they hatch from eggs usually laid on water plants. The nymph is not the beautiful creature that might be expected from its name, but a dull brown insect. They breathe through gills, which are internal in the dragonfly but look like three little fan-shaped tails in the damsel-fly.

These creatures should not be put into aquariums with small fishes or tadpoles, for they are fierce hunters and will eat any small animal or insect they can catch. They do so by lurking in water weed until some small creature comes close enough, and then shooting out their mouthparts, which work rather like a moveable arm or “lazy tongs” to grab and hold their prey. After the meal, the mouthparts are folded back against the head again.

The nymph stage may last for two or more years in some dragonflies, but finally, when the insect is fully grown, it climbs out of the water on to a waterside plant and sheds its skin for the last time. What emerges is the adult dragonfly. At first the wings are crumpled, but they dry and harden within an hour.

Most dragonflies are rather pale-coloured at first, but darken later. They often leave the water for the first part of their adult life, to spend some days or weeks feeding on insects. When they are ready to breed, they return to the water.

An adult dragonfly hunts by sight. Its antennae are tiny and its sense of smell poor, but its eyes are huge, and it can see very well. It is particularly good at detecting movement. It will fly after other insects, which it grabs and holds with its hairy legs, to eat them in flight.

A dragonfly can often be seen flying up and down a regular “beat” over the water. This is its territory, which it will defend against others of the same kind.

Damsel-flies have much the same sort of behaviour and, as their territories are very much smaller, they are easier to watch. Many damsel-flies have a sort of warning behaviour, for if another damsel-fly approaches one which is at rest in its territory, the owner of the area will raise its body as if for flight. As the body is usually brightly coloured, often with contrasting bands near the tip, a damsel-fly of the same species will be warned that the area belongs to somebody else. If it does not fly away, it will be driven off by the owner.

One of another species will usually be left alone by the territory holder, for the two species have slightly different needs, and will be able to fit in together in the same area. If the sun should go in, the dragonflies and damsel-flies will all stop flying and go to roost in waterside plants.

Although the dragonflies are large and strong predators, only a few of their eggs survive to maturity. The reason is that they have many enemies, which include water beetles, newts, fishes and birds.

This edited article about moths originally appeared in Look and Learn issue number 232 published on 25 June 1966.

A montage of moths by R B Davis

The moth that most people know best is the destructive clothes-moth, but this small pest is only one of about 2,000 different kinds found in Great Britain. They include some of the largest of all insects, and very few of them except the clothes-moth will enter houses.

Moths are close relatives of butterflies and, like them, have four large scale-covered wings and spend part of their lives as caterpillars and part as pupae. Generally, though, they are not so brightly coloured as butterflies, for they nearly all fly during the night and rest during the day.

An easy way to tell whether you are looking at a butterfly or a moth is to look at the head. This, like the rest of the body, is covered with long hairs, probably to keep it warm. The eyes are very large and enable it to see quite well, but more important are the huge antennae on top of the head. Butterflies also have long feelers, but they are like thin threads, with knobs at the end.

Moth antennae are almost always plumelike, because the antennae are used for smelling purposes.

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This edited article about butterflies originally appeared in Look and Learn issue number 231 published on 18 June 1966.

Butterflies and caterpillars

A Favourite among insects with most people is the butterfly. This insect is generally large and its beautiful, often brightly-coloured wings are easy to see. It feeds on nectar, so it is usually found in gardens or other pleasant places where there are lots of flowers.

The easiest way to find out how a butterfly differs from other insects is to look at its big wings, four in all, which overlap in such a way that they work like a single pair. They are covered, as you will find out if you touch them, with what looks like a fine dust. This “dust” is made of tiny scales of many different shapes according to their position on the wings, which are quite transparent once the scales are removed. The scales may make the wings very brightly coloured like those of the Bird-winged Butterfly from South America. Usually the colours of the underside are much duller and help to camouflage the insect when the wings are closed.

The life of a butterfly starts in the egg. These are laid on the right food plant and, although tiny, may be of very complicated shapes.

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This edited article about beetles originally appeared in Look and Learn issue number 230 published on 11 June 1966.

Various flesh-eating beetles

Beetles are found all over the world. Some survive in very unusual places because they have special habits and shapes. The Great Water Beetle shown at the top of the opposite page, unlike most kinds of insect, lives in water all its life, using its flattened paddle-like legs for swimming.

This creature is a fierce flesh eater and will tackle animals many times its own size, including other insects, fishes or newts. The lower picture shows clearly the great spines on the hind legs which are used for carving into the prey. The suckers on the front limbs, however, are found on the males only. Their function is to aid in seizing a mate.

Although they live in water, these beetles must breathe air so they come to the surface tail first and trap a bubble under their wing cases.

The species of beetle shown here is not British, but a closely-related animal lives in this country. If you have an aquarium you should be careful not to put any of these “Water Tigers” in, for they will kill and eat everything else.

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This edited article about beetles originally appeared in Look and Learn issue number 229 published on 4 June 1966.

Four species of beetle

Of all creatures on earth, insects are the most successful at survival. And among insects, the beetle seems to have evolved this pattern for success to the greatest effect.

Beetles form about one quarter of all known living animals, and there are more kinds of them than of any other single creature. They are to be found feeding on a huge variety of foods in almost every place on land where life can survive.

A beetle’s life may be long – over twenty years in the grub stage of some wood-boring beetles – but all the time it is living in the way best suited to what it is doing.

Beetles have rather unspecialized mouth-parts. In the Ground Beetle grub called Carabus, the mouth includes special parts for chewing and sucking, tasting and holding food.

Although most beetles have very definite food preferences, the lack of specialization in their jaws means that they are able to use nearly every food substance that is obtainable.

Beetles are tough animals. They are protected by an armoured shell made of stuff very like fingernails, which covers them completely. One pair of wings has been sacrificed to become “armour,” covering the top of the abdomen very strongly. Not only does this protect the beetles from their enemies, but it also acts as an insulation against water loss, which is a problem that all insects have to face. Beetles have solved it better than any others, many kinds surviving in deserts where few other animals can live.

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This edited article about insects originally appeared in Look and Learn issue number 229 published on 4 June 1966.

The oak tree is a life support system for many different species including the Oak Gall wasp (top left), by John Rignall

If you look carefully at the undersides of the leaves on an oak tree in mid-summer, you may find on some of them a number of tiny discs. They are usually a yellowish colour with brownish-red spots, and there may be as many as a hundred on a single leaf.

The discs are called spangle galls, and appear to be fixed flat on the leaf in much the same way that a stamp sticks to a letter. But if you look at one of the spangles very closely, you will see that it is actually attached to the leaf by a very thin, short stalk. Indeed, the spangles might be minute flowers growing on the leaf.

But the spangle galls are not part of the leaf: they are not even vegetable in origin like the tree. They are, in fact, produced by an insect at one stage of its life cycle.

Some weeks before the spangles appeared, the female of a small species of wasp called by entymologists Neuroterus Baccarum, laid a number of eggs on the leaf. In due course, the eggs hatched into grubs, and the grubs feeding on the leaf caused the spangles to appear.

In the autumn the spangles containing the grubs fall off the leaves on to the ground at the foot of the tree. Later the oak tree sheds its leaves, and these fall on top of the spangles.

Throughout the winter the spangles lie on the ground, protected from the cold by the covering of leaves. And inside each spangle a tiny grub is feeding on the spangle surrounding it.

In due course the grub becomes a pupa, and then develops into a young wasp. Throughout the rest of the winter, the little wasp remains safely encased in the remains of spangle that sheltered and fed it from its grub stage.

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This edited article about insects originally appeared in Look and Learn issue number 228 published on 28 May 1966.

Wasp

Man may think he rules the world, but history may yet decide that the era in which we live should not be called the Age of Mammals, Man, or the Atomic Age, but the Age of Insects.

Today we know of about three thousand different sorts of mammals, of which human beings, whatever their colour or race, are only one kind. But there are nearly a million different sorts of insects, and more are discovered every week. Many kinds of insects exist in huge numbers; there may be more individuals in a single swarm of locusts than there are people living on earth!

The bodies of insects are built in articulated sections or segments. Each segment is protected and supported by a hard covering, which acts as a skeleton, for insects have no bones. The segments are grouped into three main areas: the head, the thorax and the abdomen; they also have up to three pairs of legs and two pairs of wings on the thorax, and a single pair of feelers or antennae on the head.

Insects cannot live in the sea, but otherwise they are found almost everywhere, from high mountains to swamps or deserts as well as in less extreme environments. No single insect lives in all of these places, but between them they have occupied the world very fully.

Most sorts of insects feed on very few things; anybody who has ever kept silkworms or other caterpillars knows how selective they are about the sort of leaves they will eat. Some seem to make a very odd choice and may, for example, feed only on the leaves of stinging nettles or the decaying wood of a single kind of tree. Others, however, will eat a lot of different food.

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This edited article about nature originally appeared in Look and Learn issue number 223 published on 23 April 1966.

The cacique’s unusual pendulous nest (top left) by DEW

There is a bird known as the yellow-tailed green cacique living in the northern parts of South America. It is one of the tropical orioles that weave nests of dried grass that look like long narrow sacks hanging from the branches of the great ceiba trees. Some of these hanging nests are as much as six feet long, with an opening at the top for the birds to enter. The hen cacique lays her eggs in the bottom of the sack.

If you could stand in one of these tropical forests, watching these hanging nests gently swaying as the branches move, you would naturally wonder why the birds went to all this trouble. Indeed, why do some birds go to so much trouble to build elaborate nests? We might say it is to provide a warm and comfortable bed for the nestlings that will later hatch from the eggs. But the ordinary cup-shaped nest does this, much more simply.

We might say it is to keep the eggs safe from marauders, but there is probably no kind of nest ever built which keeps the eggs absolutely safe. In spite of all the cunning devices employed in making nests, none is secure from every kind of egg-robber just because of its shape.

The cacique’s nest is no exception, and in the South American jungles there are as many egg-robbers as anywhere else in the world. There are four-legged animals, such as the ocelot, which is a large member of the cat family. The ocelot is a tree-climber which, hunting at night, quite often catches birds roosting in the trees, or robs nests. It would have difficulty in reaching a nest of the kind described here.

During the day, however, there are other nest-robbers on the prowl, particularly large lizards and tree snakes. Both of these would be able to find their way into such a nest, do their deadly work and climb out again. And this is especially true for the snakes.

Whether it is by accident or design, naturalists report that the cacique often builds where there is a wasps’ nest, made by wasps with a particularly vicious sting. And to all appearances it looks as if there is a secret pact between the birds and the wasps to leave each other alone.

The wasps are apt to use a fork in the tree for the nest, or in the angle between the trunk and the branch. It is just the place a lizard or a snake must pass over to get out on to a branch to attempt to rob the caciques’ nests.

Wasps do not sting unless provoked or disturbed, but this is easily done! In this case, if the nest is shaken, or even touched, the wasps, who are very sensitive to such things, come swarming out. Then they are likely to sting the first living thing they meet. A lizard brushing against the nest, or a snake crawling over it, will arouse the wasps to a fury, and this is quite enough to make the would-be robber turn tail and beat a hasty retreat.

There may be as many as fifty caciques’ nests on one branch, but one wasps’ nest strategically placed on the trunk acts as a sort of permanent police patrol against robbers. And, since these birds eat only fruit and nectar, and have no occasion to go near or interfere with the wasps’ nests, they do not incur the enmity of the wasps.

However, this is not the end of the story. In South America there are no cuckoos, but there are cowbirds, which behave like cuckoos, and the giant cowbird, especially, lays its eggs in the cacique’s nest. The wasps make no attempt to drive the cowbird away!

This edited article about beetles originally appeared in Look and Learn issue number 196 published on 16 October 1965.

The destructive cockchafer grub (next to bottom) can be seen in February by R B Davis

The bumbling brown beetles which swarm through the dusk of late May evenings and bang against lighted window panes have several names – cockchafers, May bugs or June bugs.

Despite their clumsiness, these winged beetles are destructive, for they find their food by stripping foliage from trees. Their grubs are even more dangerous.

The cockchafer grubs are fat, white and fleshy, living in underground cells in which they curl themselves up crescent-wise. There they feed upon the life-giving roots of corn, grass and young nursery trees, killing off the plants.

These grubs, or larvae, live underground for up to four years, digging themselves in deeper during frost. They have hard brown heads with powerful jaws, and their bodies have three pairs of legs. The adult cockchafers emerge in the autumn but remain underground asleep until the late spring, when they spread their transparent wings and stagger off into the evening air.

The adults last only a few weeks and are in constant danger from night-time enemies – owls, bats and hedgehogs. The presence of swarms of cockchafers gives warning that nearby their grubs are probably just below the surface of the soil.

The grubs have their own enemies, too. They are the prey of moles, birds, or even pigs and poultry rooting in the soil. They have only one good use, and that is as fish bait.

The European cockchafer, belonging to the scarabaediae family of beetles, is destructive chiefly to unimportant vegetation. But its counterpart in North America, the May beetle, often does great damage to strawberry plants and cornfields.