Dragonflies (Focus - Sept)

This year’s long warm and dry summer has been mostly favourable for dragonflies and damselflies, which together are known as Odonata. In contrast to butterflies, many odonata species have long flight periods. The emergence of adults from their aquatic larval stages is not synchronised so, in the right weather conditions, some species can be seen at any time between March and September. As long as the nights do not get too cold, and there are no long periods of wet weather (when they cannot hunt), the larger dragonflies can keep flying well into the autumn. Warm, dry days and evenings will give them plenty of time to feed and mate. As the males often fight over breeding territories, and dragonflies may be attacked as potential food by the hobby falcon, by late summer they can look so badly damaged and worn out that you wonder how they keep flying. Unlike several species of butterfly, dragonflies and damselflies do not hibernate as adults. Eventually they will become too damaged, or a sharp frost will bring their lives to an end. By then they should have mated, and the females laid their eggs in a suitable water body. The resulting carnivorous larvae will then spend months developing underwater, before emerging as flying adults in the following summer. Unfortunately, extended dry spells such as we have had this year can dry up their breeding habitat and the larvae lost, so the “good” summer is not necessarily all good news for odonata.

At 57 species, the list of odonata recorded in the UK is about the same size as that for our butterflies. A number of these, with very exacting habitat requirements, became extinct last century. However, the list is undergoing a period of unprecedented change as, in recent years, a number of species have been discovered for the first time. Some of these have gone on to become breeding species. This is largely a result of climate change, which is allowing a number of insects to expand their range northwards through Europe and across the channel. Notably, this summer has seen increased numbers of the strikingly marked Jersey Tiger Moth being seen in southern England. Once only plentiful in the Channel Islands, since 1990 this day flying moth has spread north and east from its mainland strongholds in south Devon, and several have been seen in and around Tisbury. It has become sufficiently numerous to be added to the list of target species for the national Big Butterfly Count.

And now, news comes that a species of butterfly from Southern Europe has been spotted in the UK for the first time. The Southern Small White, which even on close inspection doesn’t look that much different to a Small White, a Green Veined White or, er, a small Large White, just makes life more difficult for the butterfly recorder. It’s easy to see why most of us lump them all together as “cabbage whites”.

​Andrew Graham