SOCIAL WASPS IN SUFFOLK G. D.
As everyone is aware, wasps can give a painful sting. T h e venom, a mixture of proteins and enzymes, is injected through a barbed 'sting', which is a modified ovipositorâ€”wasp queens discharge their eggs directly from the body and not through an ovipositor. Male wasps lack a sting. Occasionally people are killed by a wasp sting as a result of anaphylactic shock, and clearly wasps are a nuisance when they forage for fruit or jam, but generally wasps are beneficial as far as man is concerned. They feed their larvae on large numbers of small insects. Wasp larvae are white 'maggots', which are sometimes used as bait by fishermen. Fertilised q u e e n wasps overwinter in the solitary State and begin to forage for food in spring. They then build a 'paper' nest for a small brood, which is fed by the q u e e n . Initially the nest consists of a central pedicel with a spherical envelope, open at the bottom, containing a few cells with an umbrella-like roof pointing downwards. As the colony grows, the workers take over feeding f r o m the queen and enlarge the nest so that eventually there are several combs. In England the nest is not used in the following year. I found several in the roof of my house when it was retiled recently. Wasps macerate plant fibres with a fluid f r o m their mouths to make 'paper' for their nests. T h e common wasp, Vespula vulgaris (Linn.), uses decayed wood to m a k e its nest, which is light brown, but the G e r m a n wasp, V. germanica (Fab.), uses sound wood and makes a grey nest. These wasps' nests are often 12 in or more across, and are usually in holes in the ground, but not necessarily so. It was the ability of wasps to m a k e 'paper' that started the m o d e r n paper-making industry in E u r o p e , and it followed the observations of the French entomologist R e a u m u r (1742). T h e seasonal Variation in the numbers of common insects such as wasps are seldom recorded, but social wasps are among the insects trapped at B r o o m ' s Barn Experimental Station at Higham, Bury St. E d m u n d s , throughout the year. D r . M. E. A r c h e r , of St. J o h n ' s College, York, h a s b e e n i d e n t i f y i n g t h e
Nat. Soc. 19
Suffolk Natural History, Vol. 19
wasps caught in Rothamsted light traps and in the suction traps of the Rothamsted Insect Survey (Taylor, 1974) at Broom's Barn and elsewhere since 1972, and he edited Part 9 (Hymenoptera: Vespidae) of the Provisional Atlas of the Insects of the British Isles, which shows the known distribution of the British social wasps. Table 1 shows the numbers of the German wasp and of common wasps caught in a suction trap sampling air at 40 ft over grass at Broom's Barn in recent years. The trap takes in 100,000 cu ft of air every hour and runs continuously. In Table2, the average catch at Broom's Barn is related to that of a similar trap at Writtle, in Essex, its nearest neighbour, which has not been operating quite as long as the Broom's Barn trap, and to the average catch of other suction traps in England. Table 2 also shows the few wasps caught in a Rothamsted light trap ('moth trap') at Broom's Barn, and those caught in a small suction trap operating at 5 ft from the ground, which samples only l/6th as much air as the higher trap. In 1981 a nest of V. germanica about IV2 in. in diameter was made on the ceiling of a small concrete building a few yards from this suction trap. The suction trap catches suggest that the numbers of German wasps Aying in East Anglia may be larger than those of common wasps, but too firm conclusions should not be drawn from the catch of a Single trap in any one area, and possibly common wasps and German wasps tend to fly at different heights. However, the numbers of common wasps caught at Broom's Barn were well below the national average (although the numbers caught at Writtle roughly equalled it) and the numbers of German wasps at these two sites were above national average. The Atlas shows that since 1950 there are records of German wasps from roughly four of the kilometre squares in East Anglia for every three squares where common wasps were reported, and so common wasps are probably less widely distributed and significantly less abundant in East Anglia than German wasps. In addition to these two species of social wasps the suction trap at 5 ft caught four tree wasps (Dolichovespula sylvestris (Fab.)) and the suction trap at 40 ft caught one red wasp (Vespula rufa (L.)) in 1975 and two in 1981. Two other social wasps occur in England, the Norwegian wasp (Dolichovespula norwegica (Fab.)), which is most plentiful in the north and west of England, and the relatively rare cuckoo wasp (Vespula austriaca (Panzer)), which is a social parasite in V. rufa nests, but there is no record in the Atlas of these being found in Suffolk since 1950. However, to quote the Victoria History of Table 1. Total numbers ofsome social wasps caught in a suction trap at 40 ft., Broom's Barn, 1972-82.
V. vulgaris V. germanica
V. vulgaris V. germanica
Trans. Suffolk Nat. Soc. 19
SOCIAL WASPS IN SUFFOLK
Suffolk (1911) 'The males of V. rufa may sometimes be freely found upon Angelica flowers, and Mr Tuck has observed nests of V. sylvestris built, like a martin's, beneath house eaves in August. The rare V. norvegica has been noticed nesting at Aldeburgh, Tostock, and twice at Lowestoft in recent years; it constructs nests in trees and bushes, often in gardens, of the size of a cricket ball.' Lists of species of insects found by naturalists in their own locality can be of considerable interest to specialists in the subject, both at the time and in the future, but I think that it is equally important, or even more important to record fluctuations in insect numbers from year to year. Major changes in the insect population can then be related to the weather (e.g. the numbers of some insects may greatly increase during a hot, dry summer) or to loss of habitat, the current use of pesticides by farmers, or other factors. Of course this is not an easy task. A survey must be done with as little bias as possible over several years to establish the ränge in numbers which can be expected without any m a j o r change taking place, before any significant changes can be recognised. Dr. Archer may make use of the Rothamsted Insect Survey data for a study of the type I have in mind. I thank him for permission to publish the data collected in Suffolk so far. Table 2. Average numbers of some social wasps trapped annually from 1976-80. Broom's Barn Writtie National average (20 traps) V. vulgaris 4 Suctiontrap a t 4 0 f t . 14 15 7 Suction trap a t 5 f t . 7 Light trap V. germanica Suction trap a t 4 0 f t . Suctiontrap a t 5 f t . Light trap
35 130 3
References (Ed.) Archer, M. E . (1978). Provisional Atlas of the Insects of the British Isles. Part 9, Hymenoptera Vespidae—Social wasps. Nature Environment Research Council, Institute of Terrestrial Ecology, Monks Wood Experimental Station, Huntingdon. (Ed.) Page, W. (1911). The Victoria History of the Counties of England. Suffolk 1. Constable & Co., London. Reaumur, R. A . F. de (1742). Memoirespour servir ä l'histoire des insects. 6 233. Paris. Taylor, L. R. (1974). Monitoring changes in the distribution and abundance of insects. Rep. Rothamsted exp. Stnfor 1973. Part 2, 202. Dr. G . D. Heathcote, 2 St. Mary's Square, Bury St. Edmunds.
Trans. Suff olk Nat. Soc. 19