Help butterflies with rotten apples in warm winter

This video from Britain says about itself:

Winter hibernation – Winter’s Tale – BBC

13 December 2010

While many animals in the natural world tough it out during the harsh winters, some have a rather more dramatic and yet silent solution – sleep! A tiny dormouse nestles in the undergrowth whilst peacock butterflies and lesser horseshoe [bats] slumber in a castle dungeon in this breath-taking clip from A Winter’s Tale.

Translated from the Dutch Vlinderstichting entomologists:

21 Dec 2015 – The small tortoiseshell, peacock and brimstone butterflies spend Christmas normally hidden in a barn, a hollow tree, overwintering in a conifer or between ivy. But this year’s winter did not begin in December and there are daily reports of butterflies. On the warmest ever December 17, no less than six species of butterflies were seen.

The average temperature since the beginning of the month is nearly ten degrees above normal. Almost every day in December therefore butterflies have been seen. The high temperatures mean that the wintering butterflies brimstone butterfly, peacock, small tortoiseshell and comma have not gone into hibernation. If it’s sunny, they are active, and we can see them flutter or sunbathe on a sheltered spot. Many red admirals, which migrate south normally, have remained in our country. There are also small and large cabbage white butterflies. Probably these butterflies, which typically overwinter as pupae, came out of their pupae much too early because of the high temperatures.

We have often been asked whether this is good for butterflies, continuing for so long flying. That is not the case unfortunately. Butterflies while flying consume energy. In summer they can amplify this energy by drinking nectar from flowers. But in December, there is not very much nectar any more, so they eventually become less fit in winter. So it is better for the butterflies if the temperature drops. When it gets cold and they go into hibernation, their entire body is set to minimize the loss and then they have the greatest chance of survival.

We can in the lay out of our garden take into account butterflies in winter. Due to climate change we see butterflies earlier in the year, and they fly for longer, so we must ensure that there is year-round food for them. Flowering plants from January to December are desired. There are plants such as winter heath and Viburnum, which bloom in winter and thereby have fuel for butterflies.

For the red admiral, we can also bring rotting fruit. Increasingly red admirals remain in our country in winter, rather than leaving in the fall to lower latitudes. They have no hibernation, and at high temperatures they are quickly activated. Red admirals love rotting fruit and by putting rotten apples, bananas and grapes outside on a dish they can collect energy there. Thus, they have a greater chance that they will survive winter and will be able to reproduce successfully in spring again.