Driving around in the heat of a summer’s day you will be overwhelmed by the fluidity and amount of butterflies moving about. Many people confuse butterflies with moths. Put simply a butterfly belongs to any of several groups of mainly day-flying insects of the order Lepidoptera, (the butterfly and moth family). There are about 20 000 species of butterfly worldwide, and South Africa is home to more than 660 of these. Many are endemic, being found nowhere else in the world. I have recently been asked to plan a photographic safari in search of butterflies in South Africa so I thought I would share with you some of the truths about butterflies I have came across along my way.
Like other similar insects, a butterfly’s life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal, meaning they are active during the day. Butterflies have large, often brightly coloured wings, and a conspicuous, fluttering flight. They have organs for hearing and some species are also known to make stridulatory and clicking sounds. Vision is well developed in butterflies and most species are sensitive to the ultraviolet spectrum. They feed primarily on nectar from flowers, some also derive nourishment from pollen, tree sap, rotting fruit, dung, decaying flesh, and dissolved minerals in wet sand or dirt. Butterflies are important as pollinators for some species of plants, capable of moving pollen over much greater distances than wind. Although butterflies are an attractive prey for many predators, however, they rely on cryptic colouration, deception, or camouflage to avoid detection. Butterflies cannot sting, but many are distasteful, or even poisonous to predators.
To advertise the fact that they are unpleasant to eat, these species have evolved bright warning or aposematic colouration and markings. Red, black, yellow and white, or some combination of these, are typical aposematic colours.
Many butterflies migrate over long distances. Particularly famous migrations are those of the Monarch butterfly from Mexico to northern USA and southern Canada, a distance of about 4000 to 4800 km. Butterflies have been shown to navigate using time compensated sun compasses. They can see polarized light and therefore can orientate themselves even in cloudy conditions. The polarized light in the region close to the ultra-violet spectrum is suggested to be particularly important. It is suggested that most migratory butterflies are those that belong to semi-arid areas where breeding seasons are short. Vision is well developed in butterflies. Many species show sexual dimorphism in the patterns of UV reflective patches. One of the most striking things about butterflies is their brilliantly coloured wings, which are in fact created by minute scales. These scales are pigmented with melanins that give them blacks and browns, blues, greens, reds. Their brilliant iridescence is usually created not by pigments but by the microstructure of the scales. This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales. The scales cling somewhat loosely to the wing and break off easily without harming the butterfly.
Wing markings called eyespots are present in some species; these may have an automimicry role for some species. In others, the function may be intraspecies communication, such as mate attraction. In several cases, however, the function of butterfly eyespots is not clear, and may be an evolutionary abnormality related to the relative elasticity of the genes that encode the spots. The joy of butterfly watching is that you can do it anywhere, out in the bush, in the mountains, forests, at the coast, or in a park or garden. Patience and perseverance will go a long way.