Butterflies - Magic of Nature
Butterflies are probably the best known and loved of all insects. There are about 180.000 species of butterfly in the world and every year about 500 more are discovered. Scientifically the butterflies are divided into two groups, butterflies (day butterflies) and moths (night butterflies). The butterfly generally has brightly coloured wings which it closes when resting. The moth on the other hand is often quite drab and rests with its wings in a horizontal position. Moths are generally active at night. There are many other differences as well.
In Austria there are around 4.000 butterfly species of which 200 are day butterflies. The best known are the Brimstone butterfly, the Peacock and the Admiral. The Peacock and the Brimstone butterfly overwinter as butterflies and therefore appear early in spring time. Some species overwinter as pupae.
Anatomical structure of the Butterfly
The body parts of the butterfly are like those of practically all other insects. The body is divided into three parts, the head (caput), the thorax and the abdomen. The division into different parts facilitates the movements of the butterfly. What makes the butterfly so special are its scales, often very colourful, which cover all of the wing surface area.
The butterfly has two long antennae, with which it can sense smell. The compound eyes on its head help the butterfly to differentiate between light and dark, see the colour of flowers and sense the movements of possible predators. Butterflies only feed on liquids, which they suck up through their proboscis.
On the thorax we find the wings and legs which help the butterfly to move around. The scales on the wings are placed like roof tiles and contain specific colour substances. Each scale plays a part in the pattern on the wing. Iridescent butterflies have colourless air-filled scales. Through light refraction, these butterflies shine in wonderful hues of blue, red etc. Most butterflies have six legs with sensors for tasting and smelling and claws for grabbing and scratching.
The third body part is the abdomen. It is made up of ten segments and contains the heart, the nervous system, the digestive tract, reproductive organs and other glands, which some butterflies use to produce scents.
Metamorphosis of the Butterfly
The butterfly’s metamorphosis is a unique show. It encompasses four stages of development, egg, caterpillar, pupae and butterfly.
The dazzling colours of the butterfly are primarily used to attract the opposite sex. In a waltz like dance the female and the male fly around each other, the action often ending in mating. The ends of the individuals‘ respective abdomens hook together and the impregnation takes place. After a few days the female lays her eggs on a specific host plant. She can lay between 20 and 1.000 eggs and generally deposits her eggs on the underside of a leaf to protect them from rain and predators.
The development of tropical butterflies from an impregnated egg to an embryo, a caterpillar and finally into a beautiful butterfly is remarkably fast. The time it takes depends on species and climate, but it is often as little as a few weeks. The caterpillar climbs out of the egg and begins its main task, to eat. The first meal is the egg itself, which contains a lot of important nutrients for the further development. The caterpillar has a worm like body with a strong armored head and large jaws, ideal for eating. Inside the mouth parts there are also glands for producing webs, used to fix the pupae to a plant or to manufacture a cocoon.
At the beginning of the pupae stage, the caterpillar looks for a place suitable for pupation. Many species fasten the back end of their body to a leaf or a twig and position themselves in an upside down, hanging position. Other species spin a web round their body and the twig and spend their pupae stage in this girdle, head up. From the outside the pupae appears motionless, but inside, the transformation from caterpillar to beautiful butterfly is taking place.
In the end the pupae opens and the butterfly crawls out. At the beginning its skin is quite soft and the wings are folded together. The butterfly finds a quiet place to unfold its wings. It pumps blood and air into them, until they reach their final size and beauty. After one to two hours the wings are hard and the butterfly can take to the air.