Most of adult higher insects have wings. The wings are attached to the spinal part of the thorax, to the second and third segments.
The wings look like elastic membranes stiffened with a network of veins. Through these veins, at the time when the wings were formed, nutrients were coming with hemolymph (insect’s blood). Then the veins hardened and became a kind of framework for supporting the wings in flight.
How many wings do insects have?
Let us look at a dragonfly. It is straightforward to see that it has four wings. The front and the hind wings look almost the same; in flight they move independently.
Bees and wasps also have two pairs of wings. However, their front and hind wings are fixed together by special denticles, and they move in flight as a one big wing.
There are two-winged insects, for example, flies and mosquitoes. In the process of evolution, their hind pair of wings turned into club-shaped appendages — halteres, which are rich with sensitive hairs.
How many wings do beetles have?
Probably, everyone has seen how beetles fly, ladybirds, for example. They raise their hard wing covers, stretch from under them transparent wings, begin to flap them — and fly. So, do they have two wings? No, four: the wing covers are also wings hardened and modified in the process of evolution. In flight, they do not move, though help beetles to glide; closed, they protect from damage the fragile hind wings and soft top part of the abdomen.
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What does the character of insects’ flight depend on?
Let us recall the flight of butterflies. Their wide wings exceed in size the rest of the body. With such wings, it is hard for them to cope with wind; therefore they prefer to hide in grass if there is strong wind.
Bumblebee’s wings are smaller compared to the size of the body. And it flaps them so frequently (190-240 time per second) that they cannot be seen; they just buzz like a propeller. With such wings, bumblebees are not afraid of wind.
Fly’s wings are also small. When threatened, a fly can fly away so quickly that a human eye hardly can spot it.
Does it mean that insects with small wings fly better than those with large wings? Not always. For example, dragonflies have large wings and fly very fast, quickly change the direction of flight, can turn over in air. Hummingbird moths (Sphingidae) flap the wings so quickly, that one sees only iridescent shining! They can fly at 54 km/hour! These moths not only fly fast, but also can stop in flight — and in this hovering state sip sweet nectar from flowers.
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The scientific name of butterflies and moths is lepidopterans — scaly-winged. What is the origin of this name? It was derived from small scales that cover insect’s wings.
Hairs that cover bodies and wings of other insects, on butterflies’ wings became flat, transformed, and turned into scales of various forms. In even transverse rows, these scales cover the entire wings’ surface, overlapping each other like roof tiles. At the base of a wing, the scales are larger, round; closer to the edge, they became thinner and even pointed resembling hairs.The diversity of lepidopterans’ wings coloration and pattern is created not just by pigmentation, but also by the structure of scales. Besides pigmentary scales (i.e. those containing coloring matter), many species, especially tropical ones, have scales of other type — “optic”. In such scales, there is no pigment; they are colorless. Wings with “optic” adornment are especially bright; they look iridescent thanks to light refracting into separate rays of the spectrum, when it passes through the “optic” scales.