Moths adapt to cope with winter
Attenborough Nature Reserve manager TIM SEXTON focuses on its winter insect life
AS the nights draw in and the weather turns cold, most entomologists (people who study insects) who come to Attenborough tend to swap their bug nets for binoculars. While there certainly are more birds to be seen than beetles at this time of year, you’ll be amazed at the diversity of different insects remain active through the winter - and the lengths they go to survive in even the harshest of temperatures.
Few people realise that in the winter, when most other insects are lying dormant, there are a number of species of moth that are seemingly unaffected by the cold – and in fact, are often only active during this time.
One such moth was recorded for the first this Autumn when a number appeared on the exterior walls of the Nature Centre on Wednesday evening, attracted to the security lights around the building. The winter moth (pictured) is ‘on the wing’ between October and February.
The most obvious adaptation is that like many other winter flying moth species, the females of the winter moth are very different from the males in their appearance. They are much smaller and are totally flightless with only tiny dark-striped vestigial wings.
The female spends the day at the base of trees, climbing up at dusk to attract a mate and lay eggs – which are placed on the bark and leaf buds. As the production of eggs uses a lot of energy, at a time of year when it is difficult to replace, the females winter moths have done away with the ability to fly.
The second adaptation is not so obvious. The winter moth has special anti-freeze proteins present in their equivalent of blood. While their exact role is not yet fully understood by science, the proteins have an unusual repeating structure that allows them to bind to ice crystals and lower the minimum temperature at which the crystals can grow, thus stopping them from expanding and breaking the moth’s cell membranes.
Despite moths being extensively studied on the Reserve for over 30 years, the winter moth, like many of its cousins, has only recently been added to the site’s moth list – this is mostly due to the lack of recording in the colder months of the year.
As a result of constant effort moth recording, some 50 new winter flying species have been recorded at Attenborough in the last five years.