This common British butterfly is easily recognisable by its colouring. It has bright orange and black speckled wings with a row of blue half-moon spots along the edges. The underside of the wings is a dark grey and brown which acts as camouflage. The male is smaller than the female as is the case with most butterflies, the wingspan usually about two inches (50mm). The butterfly rapidly opens and closes its wings, flashing its bright colours to confuse and scare off its predators.
Habitat
Buddleia, commonly known as the Butterfly Bush, is a favourite haunt of the Small Tortoiseshell butterfly and they can often be seen on fine days sipping the nectar from its purple flowers. Other flowers, such as thistle and nettle, also attract them.
Life Cycle
Adults emerge from hibernation from March onwards. They search for a mate and then the female lays her eggs on young stinging nettles. She lays batches of between 60 and 100 eggs which hatch out into caterpillars.
Caterpillars
The caterpillars emerge from the eggs after about ten days. They are black with broken yellow lines along the sides of their bodies. The hairy spines which cover them and their bright colours are thought to give them some protection from predators. The caterpillars eat the nettle leaves and spin a web on the growing tip of the nettle. They live together until they reach about 22mm in length when they disperse to pupate. The chrysalises hang under the eaves of sheds or huts and under window sills. Caterpillars are around from May to August.
Hibernation
The butterflies are around from March until October when they hibernate in houses or outbuildings until they re-emerge in spring. Occasionally, some may emerge on a warmish winter's day but their food sources are limited and they may not survive.
Conservation Status
Although not listed as endangered, the number of Small Tortoiseshell butterflies has dropped by over 80%, particularly in the South East of England. This could be due to either global warming or the spread of the parasitic fly, Sturmia bella, from Southern Europe. Its eggs are found on nettles and it is thought that the caterpillars are ingesting them along with the leaf. The eggs then hatch out inside the caterpillar and kill them at the pupa stage. Research is on-going to establish the factors influencing their decline as butterflies, like bees, are good indicators of climate change and the state of the environment.
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