Bugs Read online

  HOW DO BUGS GET AROUND?

  Bugs have evolved a number of methods for moving around, which is one of the reasons they have become so successful at adapting to different habitats and climates.

  FLYING

  Of all the flying insects, butterflies and moths possess the largest and most beautiful wings. Their wings are made of very thin layers of CHITIN, covered with tiny scales. It is these scales that are responsible for pattern and colour, as observed on the sapho longwing – Heliconius sapho – below.

  At rest, the butterfly can move each of its four wings separately, but when it takes off, the fore and hindwings on each side lock together and the butterfly moves them as one. As the butterfly flaps its wings, it also moves them in a twisting figure-of-eight motion, and this lifts the butterfly into the air and moves it forward. Butterflies beat their wings between 5 and 12 times every second.

  Bugs such as flies, bees, beetles and wasps, including the thread-waisted potter wasp – Phimenes flavopictus – above, have very fine transparent or translucent wings. These are also made of chitin, but there are no scales present. They can vary in colour and pattern depending on the thickness of the chitin and any patterns on the surface of the wings.

  These bugs are able to beat their wings at very high speeds. Most fly wings beat around 100 times a second, and wasp wings beat up to 400 times per second. The fastest recorded wing beaters are biting midges – Forcipomyia squamipennis – which can exceed 1000 beats per second.

  The tiniest flying insects use a method known as “clap and fling” rather than conventional aerodynamics. This involves them “clapping” their wings above them, and then “flinging” them down. This creates lift, but damages the insect’s wings over time.

  WALKING

  As we have already discovered, all bugs have six legs, and all bugs use them to walk. The most efficient walking method used involves keeping three legs on the ground and moving the other three forwards. This is known as a tripedal gait.

  We can observe this walking style in the movement of the plagionotus beetle – Plagionotus astecus – on the right.

  1 – In the first picture we see the beetle standing still. In this position the beetle is standing on all 6 legs.

  2 – In the second picture the beetle lifts three legs (coloured red) and moves them forwards. As it does this, its body swings to one side. By remaining standing on two legs on one side and one on the other, it remains stable.

  3 – In the third picture the beetle lifts up the other three legs (coloured blue), and moves them forwards. As it does this, its body swings the other way.

  2 and 3 continue in alternating fashion while the beetle is in motion.

  4 – The beetle stops, standing on all six legs.

  Bugs are very adaptable, and can use other gaits. For example, if they lose a leg they are able to use a modified version of the tripedal gait, moving two legs on one side rather than three.

  SWIMMING

  Some bugs, such as the greater water boatman – Notonecta glauca – are able to swim very effectively. Often called backswimmers because they swim upside down, using their backs like a little boat, their hind legs are long and have evolved a series of hairy fronds along their edges. They use these long legs like paddles to propel themselves across the surfaces of lakes, ponds, and marshes. They catch and eat tadpoles, small fish and other insects.

  Other bugs can propel themselves through the water by thrashing their bodies like fish (insect larvae and mayfly NYMPHS), and others can even get around by squirting water out of their bottoms (dragonfly nymphs)!

  WHERE DO BUGS LIVE?

  The majority of bugs live on land, and most of them spend a lot of their time on their own. They usually live and sleep close to their main source of food, and only live with other bugs when it’s time to reproduce. As such, they are known as solitary insects.

  A number of bug species live in groups, called COLONIES. These can range from nests of a few individuals to many thousands.

  Certain bugs, like ants, some bees and termites, live in large colonies in which they have specific jobs. Groups of bugs which live in such groups are known as EUSOCIAL. Eusocial bugs cooperate with one another to take care of the young, produced by a single or a few females in the group.

  Paper wasps – Polistes dominula – are a type of social wasp that constructs open-celled nests such as the one above. They collect wood which they chew to form a papery pulp to construct their nests. Their saliva contains a sticky substance that makes the pulp very strong and also remarkably waterproof. Paper wasp colonies usually contain up to 200 individual wasps.

  INSIDE A TERMITE MOUND

  Termite mounds like the one below are home to colonies that can contain up to a million individual termites. The termites live in galleries (1) below ground level, and the mound has a sophisticated ventilation system so they don’t get too hot, including a ventilation chimney (2), which draws cooler air from the lowest point in the mound – the cellar (3).

  They venture out at night (when it’s cooler) through their escape tunnels (4), and collect food which can include plant material, wood and animal dung. They bring their goodies back to the nest where some of it is eaten. Any foraged wood or dense plant material is chewed up and then goes into their fungus combs (5) – areas of the nest where they grow fungus on the wood pulp. This fungus produces sugars that the termites use as a food source within the nest.

  Like the paper wasps, the termites mix their nest-building materials in their mouths. In the termites’ case, the mixture is mainly clay soil and their own waste material, which they mix with their saliva. They lay this down one blob at a time. When dry it is very tough and long-lasting. Some termite mounds have reached over twelve metres in height.

  BEETLES

  Beetles are a group of insects that make up the order coleoptera. They are the most diverse of all animal orders, and are found in nearly every habitat apart from the oceans and the polar regions. There are over 400,000 known species of beetle.

  Most beetles eat plant matter, but certain species such as scarab beetles eat dung, and a number are predatory, such as the highly aggressive tiger beetles.

  Beetles have two pairs of wings, but the top pair has evolved to form a hard, protective sheath which covers the delicate second pair underneath.

  Blue-spotted tiger beetle

  Cicindela aurulenta

  Length: 20mm

  Found in Asia, particularly China, Indonesia, Malaysia and Thailand

  Like other tiger beetles, this species is a quick-moving predator. It feeds on smaller insects and other small animals.

  Phosphorus beetle

  Phosphorus virescens

  Length: 30mm

  Found in west and central Africa

  Named because of its vivid yellow colour, the phosphorus beetle has very long antennae – longer than the rest of its body. Its larvae eat the wood of the cola tree, and many African farmers consider them pests.

  Cardinal beetle

  Pyrochroa serraticornis

  Length: 15mm

  Found across western Europe

  Cardinal beetles are predatory, and feed on smaller insects. Their carnivorous larvae are often found amongst loose, rotting tree bark.

  Ironclad beetle

  Zopherus nodulosus

  Length: 25mm

  Found in the southwestern US, and central and northern South America

  Feeding mostly on rotting wood and plant material, ironclad beetles get their name because their exoskeleton is one of the hardest of all insects. They are also known as the death feigning beetle, because they often play dead when attacked.

  Colorado potato beetle

  Leptinotarsa decemlineata

  Length: 10mm

  Found across the USA and Mexico

  This species gets its name because it is a major agricultural pest. It can cause great damage to potato crops, and also tomato and aubergine plants.

  Devil’s coach horse


  Ocypus olens

  Length: 25mm

  Found across Europe, North Africa, and North America

  An aggressive nocturnal predator, the devil’s coach horse eats slugs, spiders and worms. When threatened it raises its tail like a scorpion and defends itself with its large mandibles.

  Violin beetle

  Mormolyce phyllodes

  Length: 90mm

  Found in the rainforests of southeast Asia

  Named because its shape resembles a violin, this beetle has a very flat body which allows it to live in narrow gaps under bark, inside cracks in the soil and in between layers of bracket fungi. If attacked, it can secrete a powerful acid which can paralyse the predator while the beetle escapes.

  Christmas beetle

  Anoplognathus pallidicollis

  Length: 20mm

  Found in Australia

  Known as the Christmas beetle because it is commonly seen in the Australian summer month of December, this beetle mainly feeds on eucalyptus foliage.

  Longhorn beetle

  Pachyteria equestris

  Length: 30mm

  Found across southeast Asia

  This longhorn beetle feeds on the wood of deciduous trees and shrubs, particularly fruit trees such as lemon and apple.

  Orange ladybird

  Halyzia sedecimguttata

  Length: 6mm

  Found across Europe and North Africa

  Common in woodland environments, the orange ladybird feeds on mildew fungus and small aphids.

  Stag beetle

  Lucanus cervus

  Length: 75mm

  Found across Europe

  The magnificent male stag beetle gets its name because of the huge mandibles which it uses to fight with other males over mates, just like male deer.

  Giraffe weevil

  Trachelophorus giraffa

  Length: 80mm

  Found on the African island of Madagascar

  The male giraffe weevil gets its name from its long neck which, like the stag beetle, is used during fighting for a mate.

  Caterpillar hunter

  Calosoma scrutator

  Length: 30mm

  Found across North America

  As its name suggests, this ground-living beetle predates on caterpillars. It can release a substance when attacked which smells like rotting milk!

  Green tiger beetle

  Cicindela campestris

  Length: 15mm

  Found across Europe

  Another predatory species, the larvae of the green tiger beetle dig holes in the ground to catch smaller insects such as ants.

  Green carab beetle

  Calosoma schayeri

  Length: 27mm

  Found across Australia

  This beetle is attracted to bright lights and so is often seen in city centres!

  BEES, WASPS AND ANTS

  Bees, wasps and ants make up the insect order hymenoptera. There are over 280,000 known species in the order.

  The order contains a number of species with highly evolved social systems, such as honey bees and ants.

  Most hymenopterans have thin, membranous wings. Some of them, such as ants, only have their wings for a portion of their adult life before they shed them.

  Many of them also have a powerful sting at the tip of their abdomen, which they use as defence against predators. The sting is unique to hymenoptera.

  Tarantula hawk

  Pepsis mildei

  Length: 25 - 50mm

  Found across the southern USA through Central America to northern South America

  This species gets its name because it hunts and feeds on tarantula spiders.

  It has an extremely powerful and painful sting, second only to that of the bullet ant.

  Orchid bee

  Euglossa imperialis

  Length: 19mm

  Found across Central and South America

  The orchid bee gets its name because it feeds on orchid nectar and as such is of great importance in the pollination of orchids.

  Emerald cockroach wasp

  Ampulex compressa

  Length: 20mm

  Found in southeast Asia and tropical Africa

  Also known as the jewel wasp, the female of this solitary wasp species paralyses a cockroach with its toxic sting before laying an egg inside it. When the larva emerges it feeds on the dying cockroach.

  Yellow meadow ant

  Lasius flavus

  Length: 20mm

  Found worldwide

  This ant species lives in grassland areas, and feeds on honeydew secreted by aphids living in the soil around the roots of the grass.

  Red bull ant

  Myrmecia gulosa

  Length: 25mm

  Found across Australia

  These ants are aggressive predators able to kill and feed on larger insects such as bees.

  Green-headed ant

  Rhytidoponera metallica

  Length: 6mm

  Found across Australia

  Green-headed ants have a widely-varied diet, feeding on everything from beetles and termites to plant material, particularly plant seeds.

  Weaver ant

  Oecophylla smaragdina

  Length: 6mm

  Found across Asia and Australia

  Weaver ants get their name because they create nests in the tree canopy by weaving leaves together with silk made by their larvae.

  Bullet ant

  Paraponera clavata

  Length: 25mm

  Found across Central America and northern South America

  The bullet ant gets its name because of its sting. It is reputed to be the most painful of any insect species. The sting toxin is extremely powerful and can cause paralysis in humans.

  BUTTERFLIES AND MOTHS

  Butterflies and moths make up the insect order lepidoptera. There are over 200,000 known species in the order.

  Both butterflies and moths have evolved a huge variety in wing pattern and colouration. Some use earthy colours as camouflage, while some have developed patterns that look like eyes, to scare potential predators. Others have very bright, striking colours that help them attract a mate, or warn predators that they are poisonous.

  Most butterflies and moths feed on nectar or sap from plants, but some live purely on fat reserves they stored up during their larval stage.

  White dragontail

  Lamproptera curius

  Wingspan: 50mm

  Found in southeast Asia, particularly India, southern China, Indonesia, Malaysia and Thailand

  The white dragontail is a species of swallowtail butterfly which is always found near streams or rivers, and is a rapid flyer.

  Blue morpho

  Morpho helenor

  Wingspan: 115mm

  Found across Central America and northern South America

  The iridescent blue morpho typically feeds on the juices of rotting fruit.

  Dido longwing

  Philaethria dido

  Wingspan: 110mm

  Found across Central America and northern South America

  The dido longwing usually lives high in the Amazonian forest canopy, but flies down occasionally to drink from mineral-rich streams.

  Peacock butterfly

  Aglais io

  Wingspan: 50mm

  Found across Europe and Asia

  The peacock butterfly uses the distinctive eye-like markings on its wings to scare off small birds, and sounds to scare off rodents.

  Viceroy

  Limenitis archippus

  Wingspan: 65mm

  Found across North America and Mexico

  Viceroy caterpillars feed on willow wood, which builds up concentrations of salicylic acid, making them foul-tasting to potential predators.

  Garden tiger moth

  Arctia caja

  Wingspan: 60mm

  Found across Europe, central Asia and North America

  The brightly-patterned wings of the garden tiger moth act to scare off potential predators,
warning them that the moth contains poisonous toxins.

  Elephant hawk moth

  Deilephila elpenor

  Wingspan: 60mm

  Found across Europe and Asia

  This moth has extremely good vision in low light, which enables it to find flowers at night to feed on nectar.

  Giant atlas moth

  Attacus atlas

  Wingspan: 250mm

  Found in tropical southeast Asia

  The female giant atlas moth is one of the largest of all moths. Neither the male nor female feed – they live on fat built up during their larval phase.

  Io moth

  Automeris io

  Wingspan: 70mm

  Found across

  North America

  The io moth is nocturnal, and spends the day hiding in yellowing leaves. It uses the eye-like pattern on its wings as a defence against potential predators.

  Madagascan sunset moth

  Chrysiridia rhipheus

  Wingspan: 85mm

  Found on the African island of Madagascar