ANTLIONS IN THE SUFFOLK SANDLINGS
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ANTLIONS IN THE SUFFOLK SANDLINGS E. J. M. KIRBY Any rare or unusual animal attracts disproportionate attention and, in the context of Britain, the antlion (Euroleon nostras) is both. Over the past few years it has been realised that the insect is established in parts of the Sandlings (Plant, 1998; 1999). Having seen antlions in Australia, I was curious to find out more about the local species. Because of its former presumed absence and present rarity it was difficult to find much easily accessible information and what there was often did not answer questions which quickly sprang to mind. This note describes some observations about its structure and life history made around Westleton and Dunwich during 2000. Distribution of pits With practice antlion pits were easy to recognise; they were circular in outline, ranging from about 20 to 55 mm in diameter measured from the crest of the pit (Figure 1). They were found where there was fine sand, generally overhung by a mat of roots and top soil or vegetation (Plate 1). Such conditions were found in the abandoned sand quarries which occur throughout the Heath, in Dunwich forest in places where a bulldozer had dug a shallow trench and on roadsides where a vehicle had gouged out a part of the verge (Plate 2). High concentrations of pits were found where rabbit holes had been dug into sandy banks but which were no longer used. The quantities of fine loose sand, free of encroaching vegetation, necessary for pit making appeared to be the result of natural erosion as well as the activity of mining bees or wasps or rabbits and other creatures. In places the concentration of pits was up to the equivalent 350/m2 , for example on the floor of a large unused rabbit or fox hole. Sometimes, where they occurred along the margin of an overhang the edge of one pit abutted on that of its neighbour. Active pits were seen from May when observations started until early in October. The presence of an antlion was occasionally confirmed by gently scooping out the sand from the centre of the pit with a 35 mm film canister and trickling it out onto the palm of a hand or by sieving. Sometimes the insect made its presence known by flicking sand out of the pit, presumably stimulated by movement near the pit. Sometimes, repeat visits to a known site revealed no active pits; this usually occurred after heavy rain which had flattened out the topography but further examination showed that antlions were present in the damp sand but were unable to reconstruct their pits until the sand had dried out. After 16 September, when 34 mm of rain fell, no pits were seen in areas where larvae has been present and after this several heavy falls of rain and the lower evaporating power of the atmosphere prevented the sand from drying out. The search for antlion pits was in no way a serious census. Many possible sites were not visited and, where antlions were known to be present, places difficult of access were not explored but even so more than 3000 pits were seen.
Trans. Suffolk Nat. Soc. 37 (2001)