Summer2006
The Suffolk Argus temperature has risen to the 30°C necessary for flight, it will either fly, or turn around until its body and wings are facing directly into the sun minimising heat uptake from then on. The cryptic markings on the hindwings are all that remains to be seen when the forewings are folded back, and the orange patch around the apical eyespot is· lost from view. Against sand, gravel or dead wood, the butterfly is extremely difficult to spot, even if you saw accurately where it landed; only when it flies off at your approach, does it become visible again. Taking nectar in the sun, it is less cautious, and may even open its wings partly, so look on the heather blossom for best results. Sometimes described as human friendly, they do seem to take an interest in passing humans, and bright T-shirts are said to attract them. A male alighted on Alex's pink blouse in the King's Forest this summer, and stayed for several minutes whilst I tried to focus the camera. What I did not see this year in West Suffolk, was any quantity of Graylings. In the recent past, I have found a dozen or more at a couple of spots on Lakenheath Warren, but this year it was just singles. I suspect that their distribution is polarising towards the Sandlings and the Brecks, leaving a bigger gap in the middle of Suffolk than is shown in the maps of Richard Stewart's The Millennium Atlas of Suffolk Butterflies - a visible change even over a 5-year period. [See map opposite for the latest picture) It has not been seen at Wortham Ling for some years, and our 2005 field visit sought to discover whether it was still present, but sadly failed to prove that it was. Late in summer, the females visit clumps of grass and lay eggs singly, usually on a dried brown sheath, rather than on a growing blade. On one of our field trips a couple of years ago, some members were lucky enough to watch one laying an egg on apparently dead grass on the margins of Sizewell Beach. The larvae hatch in autumn, but do not feed much before hibernating, still as tiny caterpillars, at the base of a tussock. When fresh grass begins to grow in spring, they start to feed in earnest, climbing up the stems at night to eat the growing blades out of sight of predators. Moth
Graylings • in
Suffolk
by Rob Parker The Grayling is the largest British member of the butterfly family of"Browns", and one of the scarcest. We are lucky to have it in Suffolk, although our populations are harder to find than they used to be. ff you are interested in seeing them, read on. Grass sounds like an easily found larval host plant, but the Grayling is rather particular about the sort of grassland it frequents. It needs welldrained sandy soil, preferably slightly acidic. A glance at the UK distribution map in the Millennium Atlas of Butterflies in Britain & Ireland shows that it is found at mainly coastal sites, and hardly inland at all. The Suffolk Brecl<landprovides something of an exception, as the soils here are very sandy, and akin to the Sandlings which is our most extensive habitat. The individual grass species vary from Marram on the dunes to Sheep's Fescue on heathland, but lush green fertilised pasture is totally unsuitable. Sandy soils often support conifers, and the Grayling is happy along the edge of the forest at Tunstall or Thetford, where sparse grass sprouts along the side of a stony track. Such a place often has heather too, which is the Grayling's favourite source of nectar. The adult is on the wing in a single brood, from mid July through August, and well into September. Often there is a mass of heather at that time, but very little other blossom on the heath. It flies strongly, and often lands on the path a few metres ahead of you, only to disappear instantly; so effective is the camouflage of its undersides. Temperature regulation appears to be particularly important for the Grayling, and it basks not wings open like most species, but wings tightly closed and inclined away from the sun to catch the maximum heat on its undersides. When its body
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When did you last see a Wall Brown or a Small Heath?
to find over a longer period. In the Millennium survey, the Wall was recorded from 32% of Suffolk's 1089 tetrads, and 5 years later it was found in only 23% of the 855 tetrads surveyed. In 2005 it was recorded from only 6%, making it almost as scarce as our Biodiversity Action Plan species. The decline of the Small Heath follows a similar pattern, with 33% in the Millennium survey falling to 22%, and the last two single years hitting 17% and 20% rather less worrying than the Wall. Attention is drawn to this situation to encourage butterfly watchers to keep a special eye out for both Wall and Small Heath. Past records being often only a tick, do not throw much light on the strength of a population, so please do record numbers and comment on habitat quality when possible. Even approximate estimates of 5, 20 or 30 plus are helpful for Small Heath, once assumed to be present in hundreds, whereas Walls are more likely to be in ones and twos, •with anything over 6 being quite noteworthy. We have created a large colour sheet to catch the attention of casual recorders, and this will be deposited in country parks and forest centres, as well as being distributed to SWf branches. If you are ready to assist by distributing these to suitable places, please contact Sharon Hearle on 01638 731648. By the time you read this, the first brood will be over, but you can make a diary note to look for the second. Sightings can be sent to Rob Parker at: butterflies@sns.org.uk
by Rob Parker ff you live in central Suffolk, the chances are that you have not seen a Wall for some years, and you may have to think bard to remember whether you actually saw any Small Heaths last year. But both are what :we think of as widespread butterflies, and the Small Heath used to be really common. Sadly, both are in . decline, and this merits a bit of attention. They belong to the same family (the Satyridae, or "Browns"), and are both doublebrooded, their larvae both feed on grasses, but only in particular habitats. Both are declining, and their distribution patterns are similar, with good cover near the coast, reasonable colonies in the Brecks, and a widening void in the agricultural- areas in. between. The trend is towards the even thinner distribution pattern of their cousin the Grayling. The thin soils of the Sandlings support the right sort of grassland for the Wall, and our heaths are places where the Small Heath still flies in good numbers over sparse Sheep's Fescue, but the high nitroge_n grassland of fertilised "improved" grassland that now dominates in mos_t places is useless. Members in the west have a good chance of spotting Walls sunning themselves on the bare soil in the shelter of the banks along the Lark or the Little Ouse. May is a good time to be on the look out for the first broods, with the larger second broods reaching their peaks in August, and a few late emerging insects still on the wing well into autumn. The Wall is rather short-lived, and you have to be there during the right few days, whilst the Small Heath, being more numerous, is easier
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by DouglasHammersley
