|The emperor moth is one of the largest and most
distinctive of Europe's moths. The male is highly conspicuous as it flies
by day, darting swiftly over high forests and open moors. The emperor moth
is recognizable by its four large eye spots. It uses these spots to confuse
or frighten an attacker. The eyes on its fore wings are prominent, while those
on its hind wings can be ‘flashed’ for extra effect.
Habits: The emperor moth is found throughout Europe and Asia. It has adapted to a wide variety of habitats from high altitude forests to lowland heaths. The male and female differ in size, color, and behavior. The larger female flies weakly and only at night, hiding by day among foliage. The orange hued male is active by day and flies powerfully.
Life cycle: The emperor moth is on the wing from late April until early June. The male seeks out a mate, using his long, feathery antennae to detect pheromones – a scent given off by an unmated female. Shortly after mating, the female emperor moth searches for a plant on which to leave her eggs. The tiny, black eggs are laid at night in batches of about 20. The larvae (caterpillars) hatch within a few days and at once begin eating huge quantities of their food plant. Those caterpillars that survive develop in four stages called instars, shedding their skin as they grow through each instar. When fully developed, they spin a fibrous cocoon of brown silk. Inside the cocoon, the caterpillar molts (sheds its skin) and is transformed into a violet brown pupa (its final stage of development before becoming an adult moth).
Within the pupa a transformation takes place. All the caterpillar’s internal organs dissolve until the pupa contains only fluid. Then, cell by cell, the adult moth grows. The process can take a whole winter, and occasionally two or more years, before the adult emerges. As the pupa casing splits, the adult emerges and then hauls itself onto a stem to pump blood into its crumpled wings. Its wings must dry and stiffen before it can fly. The adult moth lives for only a few weeks. The entire developmental process from egg to adult is called metamorphosis.
Food and Feeding: The emperor moth lays its eggs on food plants. In lowland areas, blackthorn, bramble, and meadow sweet are the most common food plants. In the hills the adult chooses heather, willow, and birch. The larva has powerful, toothed jaws to cut and chew the leaves of its food plant. As the emperor moth larva grows, it feeds more each day, finally becoming as thick as a finger. It must store reserves to complete the change into an adult and to supply the adult moth with enough energy to stay alive long enough to mate. Unlike many moths and butterflies, the emperor moth never feeds.
Nature watch: The emperor moth is seen throughout its range from April to June. The brightly colored male is easier to spot as it zigzags over open ground. The eye spots on its wings also make the emperor easy to distinguish from other moths. Caterpillars are found from May to July feeding on heather, blackthorn, and other food plants. Black and orange when small, changing to green with black markings when fully grown, the caterpillars are covered with hairy bumps.
Related Species: The giant peacock
moth, Saturnia pyri.
Life cycle of the Emperor Moth:
Did You Know:
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