Ray Collier Country Diary- Emperor Moth
14th April - Emperor Moth
One of the most fascinating moths in the Highlands, the emperor moth, will soon be on the wing and it is normally found over open moorland even at some altitude in the hills. The female is the largest with a wingspan of over three inches whilst the male is slightly smaller. The male has orange under wings and grey upper wings with intricate markings. The female is generally grey with wings that also have intricate markings. Both male and female have four large and conspicuous false eyes, one on each wing and there are two theories about these unusual and striking markings. One is that if a predator sees the moth it strikes for the false eyes thinking they are head markings and while the wing or wings may be damaged the moth can still fly. The other theory is that a bird will mistake the false eyes for the eyes of a small mammal such as a stoat or weasel and will leave it alone.
Another fascinating feature is the way in which the males find the females. The antennae of the males look feathery and they have a well developed sense of smell. Newly hatched females that lack the feathering of the antennae give off large amounts of insect hormones and the males can smell these at a distance of several hundred yards. Victorian moth collectors who needed to breed this moth through to obtain pristine specimens for their huge collections used this to their advantage. They would place a newly emerged female in a container capped with muslin and then watch for the males to home in. On a good day you can see the males from some distance quartering the open moorland as they get nearer and nearer to the scent.
The emperor moth is one of the largest moths that fly by day although, intriguingly, it is only the male that flies by day as the female flies by night although they can sometimes be found sunning themselves. This may be a survival factor as there are fewer predators at night for such a large moth. The caterpillars feed mostly on heather so it is important that muirburn is carried out correctly every year so that the heather regenerates and does not die off with age. The young caterpillars look black with spots but the older caterpillars are brilliant green with black bristles. Fully grown caterpillars are over two inches in length but they are surprisingly well camouflaged when resting in heather clumps. Whilst the main food plant is heather they will also eat the leaves of bramble, elder, loosestrife and blackthorn. There are a few other large moths that fly by day in the Highlands such as the fox moth and oak eggar. One of the commonest day flying moths in the Highlands is a small but conspicuous sooty black moth aptly called the chimney sweeper. Its caterpillars feed on pignut which is why it is so often flying low over grassland.
The photograph is of a female emperor moth that surprised everyone in Farr village hall, south of Inverness, last week when it flew into the kitchen one evening. It was collected to take away to safety and on the journey to the nearest moorland it laid three eggs in the box. These hatched a few days later and are now feeding on their own patch of heather and they will eventually fly back to the wild. The thin antennae can be seen and the red marking on the outer edge of the wings is missing on one side through damage.
One of the most fascinating moths in the Highlands, the emperor moth, will soon be on the wing and it is normally found over open moorland even at some altitude in the hills. The female is the largest with a wingspan of over three inches whilst the male is slightly smaller. The male has orange under wings and grey upper wings with intricate markings. The female is generally grey with wings that also have intricate markings. Both male and female have four large and conspicuous false eyes, one on each wing and there are two theories about these unusual and striking markings. One is that if a predator sees the moth it strikes for the false eyes thinking they are head markings and while the wing or wings may be damaged the moth can still fly. The other theory is that a bird will mistake the false eyes for the eyes of a small mammal such as a stoat or weasel and will leave it alone.
Another fascinating feature is the way in which the males find the females. The antennae of the males look feathery and they have a well developed sense of smell. Newly hatched females that lack the feathering of the antennae give off large amounts of insect hormones and the males can smell these at a distance of several hundred yards. Victorian moth collectors who needed to breed this moth through to obtain pristine specimens for their huge collections used this to their advantage. They would place a newly emerged female in a container capped with muslin and then watch for the males to home in. On a good day you can see the males from some distance quartering the open moorland as they get nearer and nearer to the scent.
The emperor moth is one of the largest moths that fly by day although, intriguingly, it is only the male that flies by day as the female flies by night although they can sometimes be found sunning themselves. This may be a survival factor as there are fewer predators at night for such a large moth. The caterpillars feed mostly on heather so it is important that muirburn is carried out correctly every year so that the heather regenerates and does not die off with age. The young caterpillars look black with spots but the older caterpillars are brilliant green with black bristles. Fully grown caterpillars are over two inches in length but they are surprisingly well camouflaged when resting in heather clumps. Whilst the main food plant is heather they will also eat the leaves of bramble, elder, loosestrife and blackthorn. There are a few other large moths that fly by day in the Highlands such as the fox moth and oak eggar. One of the commonest day flying moths in the Highlands is a small but conspicuous sooty black moth aptly called the chimney sweeper. Its caterpillars feed on pignut which is why it is so often flying low over grassland.
The photograph is of a female emperor moth that surprised everyone in Farr village hall, south of Inverness, last week when it flew into the kitchen one evening. It was collected to take away to safety and on the journey to the nearest moorland it laid three eggs in the box. These hatched a few days later and are now feeding on their own patch of heather and they will eventually fly back to the wild. The thin antennae can be seen and the red marking on the outer edge of the wings is missing on one side through damage.
posted by Corinne @ 9:29 AM
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