Bug bodies are particularly well adapted to the environments in which they live,
and they have evolved many clever methods for getting themselves about. Bug
appendages may be specially adapted for running, jumping, flying or swimming.
Running and Walking
The thorax of an insect, immediately behind the head, is packed with muscles
that assist legs and wings in their work. Insect muscles tire less quickly than
human muscles. This is not because they are stronger, but because insects are
small and their muscles are strong in relation to their body weight.
Having six legs is a very big advantage for insects. They walk by moving three
legs at time, making alternate tripods of two legs on one side with the middle
leg on the opposite side. This gives insects great stability. Many smaller
insects are able to distribute their body weight evenly across their six legs
and can literally walk on the top of water.
Insects evolved on land, so those that adopted an aquatic lifestyle had to
develop new ways of moving through their environment. Many aquatic insects have
evolved middle and back legs that are flattened and look like paddles to meet
this specific need. Other insects have developed their own unique swimming
styles. Dragonfly nymphs move by sucking in water through their rectum and then
pushing it out with great force. This jet propels them rapidly over short
Insects were the first animals to fly. Monster-sized dragonflies 70cm across
flew 300 million years agobefore even dinosaurs existed. Insects were
also the only animals to develop wings from scratch. Flying birds and mammals
all modified their front limbs into wings.
Insects can hover, fly backwards, accelerate suddenly to over 150 kilometres per
hour, and perform amazing acrobatics. Their flying skills enable them to escape
predators, to take advantage of seasonal food sources in distant locations, and
to migrate to new areas.
The best fliers are house flies, which have only one pair of wings. Their back
wings have reduced to tiny knobs and are used as stabilisers. House flies have
special muscles that allow them to beat their wings 200 times a second, which
is why they make a buzzing noise during flight.