The Hemiptera and Coleoptera of Stinging Nettle (Urtica dioica L.) in East Anglia

Abstract

Stinging nettle (Urtica dioica L.) is a very widespread and abundant plant in Britain. Around buildings and in agricultural grassland it is usually considered an undesirable weed because it forms dense stands, spread by rhizomes and is difficult to eradicate. It can apparently persist for long periods on sites of human habitation and has been associated with ancient earthworks and the sites of mediaeval hearths (Greig-Smith 1948; Beresford 1971, p. 62). In the past it enjoyed a rather higher status as a source of fibres for textiles and as a basis for various culinary recipes (Grigson 1958; Masefield et al. 1969). An account roll of Ely's manor at Lakenheath for 1429 quotes 'And for 8d for nettles in the garden sold this year'. It has also long been known as a food plant for a large and diverse fauna and is commended by lepidopterists like Newman (1967) for the vanessids dependent on it. The biology and ecology of Urtica in Britain have been described by Greig-Smith (1948). With minor revisions to 0. W. Richards' list of insects in that paper, twentyseven species may be considered more or less confined to nettle, plus a further nineteen oligophagous species and a few predators closely associated with it. The fauna has not been the subject of any intensive study, perhaps because nettle is considered such a common-place plant. As a characteristic member of field margins and waysides, however, it makes a significant contribution to the faunal diversity and biomass of intensively farmed agricultural areas. The diversity of the fauna, moreover, raises questions of how and why there is such full exploitation of this host plant and its widespread occurrence makes it possible to study this in most parts of the country and to compare different habitats and soil types. Because nettle establishes itself fairly quickly under favourable conditions and rapidly achieves its full performance, it is a useful experimental plant with great advantages over annuals or slower growing woody plants. The present work was done to elucidate the life cycles of the commoner elements of the fauna of nettle and some of the more important habitat factors determining their distribution. This was considered a necessary background to studies on insect dispersal and host colonization in relation to factors such as isolation and the effects of sprays, all of which are particularly relevant to wildlife conservation in lowland Britain. These more applied aspects will be dealt with in subsequent papers. Because of the different sampling techniques required for different groups of insects, this paper is devoted to the Hemiptera (except aphids) and the Coleoptera. A few of the less common monophagous species are not covered, but several polyphagous species which were found to be locally common and important components of the fauna have been included. Nomenclature follows Kloet & Hincks (1964) for the Hemiptera and Kloet & Hincks (1945) for other groups.