Friday, 28 July 2006

A good summer for immigrants

The two buddleias that stand on either side of our rather narrow garden have come into their own over recent days, with a succession of insects arriving to nectar on the tiny pink and purple flowers. Evening has proved the best time to stand and observe (and in some cases be observed by) the butterflies, bees and moths that bustle about from flower to flower. The most numerous of these visitors has been the silver-‘y’ moth, Autographa gamma, an immigrant from the Continent that arrives, and breeds, here each summer. Numbers vary from year to year but this summer they have been truly amazing, with in excess of fifty individuals on the buddleia each evening this week.

The silver-‘y’ belongs to a group of moths called the noctuids. These are typically stout-bodied, medium sized moths with forewings substantially longer than they are deep. Most of the 400 or so British species are brown in colour but the silver-‘y’ can be identified readily by the presence of a conspicuous and unbroken metallic silver ‘y’ mark on the upper surface of the forewing. Unlike most other moths, the silver-‘y’ has an early evening feeding flight that brings it out alongside the day-flying butterflies and presents the casual observer with an ideal opportunity to get good views as it feeds.

The many butterflies have included large numbers of red admirals, another species that arrives as a summer visitor but which, thanks to global climate change, seems increasingly able to overwinter here as well. In fact, it has always been something of a mystery as to why the red admiral was unable to survive our winters. After all, the species overwinters successfully further east in colder parts of Europe. It may well be the combination of cold and wet that caused problems. These striking red and black butterflies have a powerful flight, with deep regular wing strokes. They also seem to be fairly inquisitive and of the butterflies feeding on my buddleias, they are the only one to approach right up to me as I stand by the bushes and watch. In with the red admirals are half a dozen or so peacocks, the occasional comma butterfly and, on one evening only, two painted ladies. The painted lady is another immigrant, this time from much further south, from the warmer climes of southern Europe and North Africa. Perhaps its origins explain why it seems to spend more time basking in the sun than the other species. I have been hoping that the presence of these familiar immigrants will also mean the arrival of one or more rare visitors: a clouded yellow butterfly or maybe a hummingbird hawkmoth. We shall have to wait and see.

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