Adult winter moths are now enjoying their flying stage

Northern Winter Moth NT625 421
Northern Winter Moth NT625 421

When driving along our rural roads in the winter months it is often possible to see lots of moths in the car headlights.

If it is a slow flying, fawn to light grey colour, it is most likely to be one of the winter moths.

There are several different species which are quite similar and even in the hand can be difficult to tell apart as they are variable in colour and markings.

It seems strange that in their life cycle the adult flying stage is through the winter, when they can be seen even on quite cold nights and are often abundant on damp nights with light rain.

They tend not to fly in strong winds and very heavy rain.

It would appear to me to be more sensible to fly on warm evenings in the autumn rather than in mid winter, but evolution is a strange thing, maybe they are trying to evade bats which eat a lot of moths during the warm months and will be hibernating during the cold weather in winter.

Only the male moths fly, so any that you see flying are males.The female is virtually wingless and cannot fly.

The adults emerge from the pupae in the soil from November through to February.

The female climbs up a shrub or tree where she sits and releases a scent or pheromone which the flying male can detect and he is then guided in to find the female.

This is all done under the cover of darkness when they are safe from all the insect eating birds which would devour them if they were found.

The eggs are laid amongst the buds of trees and shrubs and just as the buds start to open in the spring the young caterpillars emerge from the eggs ready to feast on the fresh, young newly emerging leaves.

In heavy infestations trees can suffer quite badly but this is seldom the case and often damage is only seen with a few holes here and there on the affected trees.

Many of our small birds, especially the tits feed their young with large numbers of winter moth caterpillars and egg hatching is timed to coincide with the caterpillars.

In an ideal world there will be plenty food for the young birds to thrive, sufficient caterpillars left over to provide for the next generation of moths and the tree will not be adversely affected.

When the green, looper like caterpillars are fully grown in June, they descend to the ground where they pupate and remain until early winter ready to start the next generation again.