Column: Autumn thoughts

The seasonal change in the garden is miraculous. We see our trees, shrubs and perennials get set for the upcoming winter sleep and are out studiously watering in absolutely everything possible to help them survive the winter well. While I am out giving everything a good drink, I noticed our insect population also preparing to survive yet another winter.

In the autumn, many insects are much more visible as we have less time in the day when temperatures are warm. When the sun shines it invites all the critters to come out and soak up the rays. This time of year we see huge populations of insects congregating wherever the sun shines and as the nights cool off, they will do almost anything to find a bit of warmth. In fact, if you have any cracks or crevices into your warm house, they will gladly take that opportunity to enter.

As fall progresses, and we get a hint of winter all of those little critters seem to magically disappear. Strangely enough, months later like a magic trick gone bad, all of a sudden they are back. How can these amazing but sometimes irritating critters manage to survive the big freeze?

Insects have a variety of ways they can survive the winter so there is no simple answer to this question. Some will survive as eggs, larvae or pupae, which are all immature life forms or some, like the ladybug will survive the winter as fully mature adults.

Avoiding the cold is one strategy that insects may take for winter survival. Take the Monarch butterfly who will fly thousands of miles to avoid the cold. Like our songbirds, once the cold begins to set in, they will head south en masse in order to avoid the cold. They will make a long journey to central Mexico while other butterflies like the Swallowtail will overwinter as a chrysalis. Other insects will simply spend the winter at the bottom of ponds or buried deep in the soil to avoid the frost. Others, like some types of mosquitoes will hide out in sheltered places in a state of quiescence awaiting their next meal in spring. Some will enter into a semi-frozen state called diapause (or suspended animation) for the winter and in spring, thaw and crawl off as if winter had never happened. Thus, these critters have mystified scientists as these insects have found a way to freeze their organs and tissues and then spring back to life when the temperature rises.

Another huge number of insects will survive in the form of eggs. Thus in spring, a whole new generation will appear. When we have an unseasonably warm winter, it is an opportunity for a species to expand their territory in areas which they may not have been able to previously survive.

Enjoy the last bit of autumn – as it has been one of the best we have experienced.

Hanbidge is the Lead Horticulturist with Orchid Horticulture. Find us at www.orchidhort.com; by email at info@orchidhort.com; on facebook @orchidhort and on instagram at #orchidhort.

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