MAIN CLASSES OF BEETLES
Blaartrektorre (Family Meloidae)
Size: Length 5-50 mm.
Colour: Usually black with bright red, orange or yellow markings.
Habitat: Found on flowering plants throughout the summer.
Among the brightly coloured blister beetles is the CMR beetle, so named because the black-and-yellow stripes across its wing-cases resemble the stripes on the uniforms of the Cape Mounted Rifles Brigade, a unit which no longer exists. The purpose of such bright markings is to advise predators to keep away, for the body fluid of these beetles contains a poison, cantharadin. On human skin it raises blisters, and it is used medicinally for this purpose. If taken internally, cantharadin can do much harm and even cause death.
For gardeners blister beetles are a mixed blessing. Their fondness for petals is bad news for flowerbeds; knowing that enemies such as lizards and birds are deterred by their warning semaphore of stripes, the beetles take their time in crawling, or noisily flying, from one blossom to another. But blister beetle larvae do sterling work by feeding on the eggs of locusts (including the notorious swarm locusts) and grasshoppers.
The female is a model of motherhood. Having laboriously dug a shallow hole in the ground, she lays eggs in it, carefully covers them over and then repeats the process, day after day, until her ovaries are exhausted. Then she dies having completed her life’s duties.
Her offspring go through several metamorphoses: the first is from egg to tiny, active, six-legged larva that must find the underground egg pod of a locust or grasshopper if it is to survive. Once entrenched in this pod it becomes a fat white grub which passes the winter months resting, to cast its skin with the advent of the warmer weather and become a pupa. Finally it emerges in all its striped – and striking glory as a beetle.
Miskruiers (Family Scarabaeidae)
Size: Length 5-50mm.
Colour: Black, brown or metallic bronze, blue or green.
Habitat: From arid desert to tropical forest.
To the ancient Egyptians the scarab or dung beetle was sacred. It is certainly a beneficial scavenger, and southern Africa has a rich supply of these insects: there are about 300 species in the Scarabaeidae family, varying greatly in size, appearance and habits. The typical scarab beetle belongs to the subfamily Scarabaeinae.
Common to these species is the habit of rolling dung into a ball. The completed ball is often many times larger and heavier than the beetle, which may then roll this precious food store energetically for several metres before burying it in a hole it digs in the ground. Mating takes place in this bridal chamber, and in due course the female lays an egg in a hollow at the side of the ball of dung. When the white grub hatches, it begins feeding on the nutritious dung store.
Some species breed above ground within a dung pad. The female lays her egg inside a small piece of the dung, then rolls this into a ball that remains within the dung pad while the larva hatches. A third type of dung beetle excavates a nest beneath a dung heap, with a tunnel connecting the two.
Generally dung beetles transport their dung pellets by pushing them backwards with their hindlegs. But the flightless species of the Namib Desert grips the pellet with its hindlegs and drags it forwards.
There are dung beetles that augment their diet by eating carrion – the flesh of dead animals. Others feed on the fungus that develops on decaying vegetable matter, and some have a taste for wild mushrooms.
Vrugtetorre (Subfamily Cetoniinae)
Size: Length 10-70mm.
Colour: Most fruit beetles are brilliantly coloured. One common species (Pachnoda) is black, with rows of bright yellow patches on the wing-cases; another is green, with yellow bordering the wing-cases.
Habitat: Orchards, flowerbeds, beehives.
Fruit beetles are strong fliers and can cause fruit and flower mayhem during the course of their day’s foraging. At night, they repair to special ‘sleeping trees’ or else bury themselves in the soil at the foot of the very plants they have been ravaging.
Roses are among the flowers most at risk, hence the name ‘rose beetle’ given to the genus Pachnoda. Almost any soft, ripe fruits, including apricots, peaches, plums and pawpaws, are also attacked; thebeetle bores into the fruit to extract thejuices. Some fruit beetles enjoy honey, fearlessly entering beehives in search of it. This species also destroys wasp nests. And there are beetles of this family that feed on tree sap.
There are also some insect-eating species regarded as beneficial. One of these likes the poisonous yellow aphids found on milkweed plants; another makes a meal of the soft brown scale insects on citrus trees.
The larvae of fruit beetles feed on decaying vegetable debris and on plant roots. The female of Pachnoda sinuata takes a trick from the dung beetle: she makes several little balls of dung (or compost) and then lays an egg in each of them. The tiny larvae that hatch feed on the contents of these balls, before transforming themselves into pupae. You may find up to a dozen of these little dung balls attached to one another within the warm, moist intimacy of an aromatic manure heap or pile of compost, or in a well-fertilised flowerbed.
GLOW-WORMS AND FIREFLIES
Glimwurms en vuurvliegies (Family Lampyridae)
Size: Length 5-25 mm.
Colour: Dark brown, tan or black.
Habitat: Woods, ditches, lawns; also in forests, bushy areas and near vleis.
Neither worms nor flies, these insects are, in fact, beetles. The family is represented by two main subfamilies: Lampyrinae and Luciolinae. The end of the abdomen lights up at night as a result of a chemical reaction between a luminous substance, luciferin, contained in the tail, and an oxidizing enzyme, luciferase, in the blood. Cells filled with tiny crystals act as reflectors. Since the light is confined to the visible part of the spectrum (that is, there is no infrared or ultraviolet), virtually no energy-wasting heat is generated.
The luminescence enables the sexes to locate each other. Among glow-worms it is the female who literally holds a torch for her mate as she radiates a steady glow. She is up to 25 mm long and wingless. She looks rather like a larva or a worm, although in the Luciolinae the females are winged. Male glow-worms have wings and resemble fireflies . Communication between the sexes is similar to that of toktokkies, and results in mating.
Both male and female Luciolinae are winged, and in this genus the male’s light signals are brighter than the female’s. He is a flasher � or, more accurately, a flickerer � as he flies through the dark, and can control the flash frequency of his signal.
Different firefly species emit different light signals -and these visual IDs are sufficient, it seems, to prevent crossbreeding among species. In southern Africa there are about 30 different species of fireflies. The larvae of these insects closely resemble the female glow-worm.
Liewenheersbesies (Family Coccinellidae)
Size: Length 0,5-12mm.
Colour: A bright, shiny yellow or red, with a pattern of black dots or crescent-shaped markings.
Habitat: Plants that are infested with aphids, mealy bugs and other pests. Cultivated crops including cucumbers, potatoes and maize.
At an early age we are taught to admire this pretty little beetle, and most species are certainly worthy of our protection since they feed, both in the larval stage and as adults, on aphids, a garden pest. Their bright colouring is, in fact, a warning to birds and other predators to keep clear. If you pick up a ladybird and manhandle it, it secretes a bitter, yellow, unpleasant-tasting liquid from between the joints of its legs.
The female lays her cluster of 20-30 yellow, elongated eggs on the underside of a leaf, conveniently close to an aphid colony. When the little, black six-legged larvae emerge they sink their sharp jaws into the aphids and suck out their vital juices. Prominent yellow or white markings develop on the growing larvae, which eventually leave their food source to pupate from a stone.
Without the action of predacious insects such as the red-and-black ladybird beetle, the aphid population would soon overrun gardens and cultivated crops. As it happens, most ladybirds are beneficial pest-controllers – but there is one subfamily of them, the Epilachninae, that are regarded as pests themselves: these are vegetarians, and they attack the leaves of a wide range of crops, especially those of the cucumber family.
Langhoringkewers (Family Cerambycidae)
Size: Length 8-75mm.
Colour: A great variation, nocturnal species being grey, brown or black; flower-eaters are brightly coloured.
Habitat: Trees, shrubs, herbaceous plants.
This family is distributed throughout the southern African subregion. ‘Long-horned’ refers to the long antennae (often longer than the body) of this large family of beetles, of which there are over 800 species in southern Africa alone. Most of them are woodborers, with enormously powerful jaws that can chomp through the hardest of woods. Fortunately, most species are interested only in weakened or dying branches and trees. By speeding up the breakdown of this wood and allowing the nutrients within it to be returned to the soil, the beetle actually performs a useful natural function.
But there are long-horned beetles that damage healthy trees and are regarded as pests. Ceroplesis thunbergi attacks wattles. Other trees at risk include willows, fig trees and orange trees. The larvae of many such long-horned beetles feed on freshly cut logs.
The long-horned beetle population is controlled in a macabre way, for the larvae are cannibals. After several of them have hatched from a group of eggs, they eat one another – until the survivors are so few and far apart that no further damage can be done. Even so, the surviving grubs take pains to avoid the burrows of their peers as they tunnel through the wood, turning in a different direction when approaching another burrow. It is thought that one of the ways by which they can detect another grub’s presence is by means of microscopic sense organs scattered over their bodies, that are sensitive to airborne vibrations.
If you hold a long-horned beetle between your fingers it is apt to emit a pathetic little noise halfway between a creak and a squeak. It is made when the back of the neck rubs against a roughened area between the bases of the wing-cases – but its purpose remains obscure.
PREDACIOUS GROUND BEETLES
Oogpisters (Family Carabidae; Anthia and related genera)
Size: Length 3-60 mm.
Colour: Black, often with white, yellow and red patches on the thorax or elytra (wing-cases).
Habitat: Widespread, but most abundant in the drier parts.
As their name implies, nearly all ground beetles are incapable of flight; but they are agile runners, and if threatened they rely mainly on their speed to escape. However, they have also developed a very effective form of chemical defence. Ground beetles of the genus Anthia and related genera secrete an abdominal substance of some organic acid, for example formic acid, which they are able to squirt out in a strongjet at an attacker.
The jet has a range of up to 30cm and can blind a small domestic animal if it is not treated immediately. The substance can also harm the human eye, and causes severe pain if it touches human skin. The Afrikaans name for the beetle, ‘eye-shooter’, draws attention to its defensive technique.
Don’t pick up this beetle with bare hands – it can give you a deep bite. The wing-cases of the Anthia ground beetle are fused together, and the membranous wings that normally would lie underneath have disappeared.
Light-coloured spots on the wing-cases advertise the fact that the beetle is unpalatable. They also alert potential predators to its vigorous defence mechanisms.
Ground beetles prey on insects, including such pests as grasshoppers and caterpillars. They are fierce hunters, searching for prey at random. Some species go so far as to defend their ‘territory’ against other beetles wishing to use the same hunting ground.
Renosterkewers (Subfamily Dynastinae)
Size: Length 10-45 mm.
Colour: Black or brown.
Habitat: Found generally on decaying wood and plant matter; compost heaps.
An unmistakable feature of the rhinoceros beetle is the rhino like horn that adorns the head of the male, making him look so top-heavy that he seems in constant danger of toppling over. The species with the longest horns, Oryctes boas, uses horns as weapons when two males do battle. This species is the largest and most widely distributed of the 60 different species recorded in southern Africa. (The southern African rhinoceros beetle cannot compare in size to specimens found in Central and South America, where this unusual-looking insect can grow to a length of 17,5cm!)
These insects have squat, lozenge-shaped bodies with protruding heads, although the bases of the antennae cannot be seen from above. They are nocturnal, and occasionally you may see one of them flying haphazardly towards a light source to which they are attracted. Beetles that have collided with a light – or a lighted window – may fall to the ground, where they lie stunned for some time before pursuing their flight again.
The larvae of rhinoceros beetles, which are white and very large are usually found in manure heaps or piles of humus, where they develop into pupae without the protective covering of a cocoon. The larvae of some species feed on plant roots, while the adult beetles nip through the stems of young shoots just below ground-level. Because of these disconcerting habits, both larvae and beetles are regarded as serious pests on cultivated land and also on lawns in particular the genus Heteronychus. Heteronychus licas damages sugar cane, while H. arator, the black maize beetle, attacks maize, potatoes and pineapples.
Toktokkies (Family Tenebrionidae; Psammodes and related genera)
Size: Length up to 65mm.
Colour: Black or dark brown.
Habitat: More arid, warmer areas, with sandy soil and little ground cover.
These conspicuous members of the large family of darkling beetles are stout, heavy-bodied and wingless, with a tough outer casing. Their habit of knocking loudly on the ground at intervals has given their name to a children’s game (knocking on front doors and then running away). The beetle makes the noise by raising its abdomen and then bringing it down on the surface of the ground several times in quick succession.
The tapping is a form of communication between both sexes. The male initiates the tapping and is answered by a receptive female. After a prolonged exchange of signals, the pair finally make contact and mate. The females lay single eggs, each about 6mm long, which they place in a shallow hollow in the ground. The long, yellow larvae that hatch live in the soil.
The mature toktokkie beetle scavenges on a variety of plant and animal debris. The Tenebrionidae family to which this insect belongs is very large, with at least 3 500 species in southern Africa.
In the Namib Desert some species survive by collecting dew from specially excavated trenches which trap moisture from banks of fog rolling in from the Atlantic Ocean. Others in the same area drink by doing a ‘head-stand’, thereby allowing condensed dew to trickle into their mouths. The Namib is also home to the fastest running beetle in the world, a Tenebrionid that scurries across the scorching sands at lightning speed. Another species boasts the longest legs in the world.
Waterkewers (Family Dytiscidae)
Size: Length up to 40mm.
Colour: Bodies pale yellow to black, or green-black with yellow margins.
Habitat: Freshwater pools and ponds where there is little or no current. The beetles are often attracted in large numbers to artificial lights.
Water beetles swim below the surface and are beautifully streamlined for doing so. When they wish to breathe they swim to the surface. The beetle comes up end-first, and an air bubble is then trapped between the two elytra (wing-cases) and the abdomen. Equipped with this new aqualung, the beetle can dive again.
Among the water beetles, the large species of Cybister is very common. It is a fierce predator of aquatic insects, small fish and tadpoles. It also owns a useful arsenal of defensive weapons, including a sharp, backward-projecting spine on its underside that can draw blood. Glands in its neck can emit a foul-smelling white fluid capable of temporarily stunning fish and frogs. Two anal glands secrete an ammonia like fluid that is discharged with a tiny explosion.
To propel itself in the water Cybister uses its powerful hindlegs, which carry stiff brown bristles. These legs can be ‘operated’ like oars: on the backward kick the bristles ‘feather’ out, offering a wide surface of resistance to the water, but when the legs are pulled back before the next stroke they are turned at an angle, so that the bristles lie flat.
Like other aquatic beetles, for example the whirligig beetle, Cybister flies well and covers large distances during the evening in the search for other bodies of water. But on land it is awkward and ill-equipped.
Kalanders (Family Curculionidae)
Size: Length 1-60mm.
Colour: Usually brown or black, and often with a camouflage pattern of other colours. The largest weevils have pink or red spots.
Habitat: An extensive range of plants, including many cultivated crops such as citrus, fines, tobacco and maize, as well as stored grains.
Weevils make up the largest beetle family in the world. There are more than 2 500 species in southern Africa alone. They are characterised by a snout or ‘ rostrum’ at the front of the head. Among different species the snout varies enormously in shape and size – from short and squat to long and narrow.
The female cycad weevil, Antliarrhinus zamiae, has a threadlike extension three times the length of her body; with it she bores into an ovule (seed) in a cycad cone, lays an egg, and shoves it to the end of the tunnel that she has made.
The leaf-rolling weevil has a short snout, and so the female resorts to other means to protect her egg. Like an origami enthusiast, she cuts out a portion of leaf and, using her legs, folds it into a neat little container into which she deposits her egg. The leaf is both protection and, in due course, food. The larvae of weevils have no legs and therefore cannot forage on the external surface of plants; invariably they develop within the plant tissue.
Weevils are commonly regarded as pests. They are perhaps most notorious for destroying stored grain. The dark red Brachycerus obesus is about 25 mm long and enjoys feeding on the newly emerged leaves of garden bulbs, including those of the gladiolus and lily.
Weevils are unusual in that they owe part of their colour to the presence of small scales which can be rubbed off.
Waterhondjies (Family Gyrinidae)
Size: Length 3-18mm.
Colour: Shiny black or grey, with a paler border to the wing-cases and back in some species.
Habitat: Freshwater pools in gently flowing streams (in which the current bears the whirligig beetle’s diet of dead or drowning insects).
Whirligig beetles are wonderfully equipped for their aquatic life. The body is smooth and streamlined; the four rearmost legs are fringed with bristles and act as efficient paddles; the front pair of legs is longer than the others and is used to catch prey or, when necessary, to cling to submerged objects.
The most remarkable adaptation is the whirligig’s dual-vision eyes. Each eye is divided into two sections, an upper part for air vision and a lower part for underwater vision. The upper part is situated on top of the head, with the lower beneath it, giving the effect of four eyes.
Whirligigs swim in groups on the surface of the water, waiting for the current to deliver their dinner. Any insect trapped on the water film is seized and consumed with relish. When alarmed, the beetles will speed up their characteristic twirling locomotion and, as a last resort, will dive below the surface, still moving around in agitation. A small silver air bubble trapped under the wing-cases serves as the whirligig’s life-support system, enabling it to breathe underwater for some time.
There are about 53 species of whirligig beetles in southern Africa, most of which can fly well. Their occasional flights take them on expeditions to other pools.
The female lays eggs in neat rows on submerged vegetation. The centipede-like larvae that hatch breathe underwater through 10 pairs of feathery gills, and feed on small insects on the bottom of the pool.