A HISTORY OF DURHAM 



DIPTERA 



Flies 



In this county the two-winged flies have been neglected. The following list of species is 

 the result of observations and collections made during the six years which formed the close ot 

 the nineteenth century and the beginning of the twentieth, before wliich time no collections 

 had been made or records kept for this county. It is, therefore, very imperfect. But it shows 

 that the county, with its great diversity of natural features, is the home of a large variety 

 of flies. 



Among the long grasses on the sand hills of the southern coast-line Asilidae and Therevidje 

 lie waiting for their prey. Along the flower-clad clifF-tops bright Syrphids and more homely 

 Anthomyids disport themselves in the sunshine. In the rush-lined gullies worn in the boulder 

 clay, Leptidae and the larger Crane flies abound, while on the beach, among the heaps of 

 seaweed left by the receding tide are many species of shore flies, both the Fucellias, Orygma, 

 Chersodromia, and others. The deep wooded denes, so characteristic of this part of the 

 coast, are the haunts of swarms of sandflies and midges of many kinds. Farther inland, 

 along the marshy flats through which runs the sluggish Skerne, and on the upland burns 

 and among the rushes of the hill pastures, the water-loving Dolichopods skim over the streams 

 and pools or lurk among the herbage. By the banks of the numerous brooks and rivers 

 where willows hang over the waters, the black Bibio of St. Mark may be found, while its 

 smaller relative of St. John and several other species swarm among the herbage. Along the 

 field borders, and in the meadows or in the neglected corners, the numerous tribes of 

 Acalypterous Muscids, hovering Syrphids, and indeed flies of almost every family, hide them- 

 selves beneath the leaves, or feed on the yellow pollen. The upper dales and the many glens 

 which seam the hillsides are the resort of great numbers of the Limnobidse. And on 

 the heathery moors the hum of the bright wasp-coloured Sericomyia mingles with that of 

 the bees. 



The county, therefore, with its considerable range of altitudes from the sea level to 

 over 2,000 feet, and its varied topography and vegetation, is well calculated to possess a fairly 

 wide range of insect life, notwithstanding its northern latitude, its eastern exposure, and its 

 often smoke-laden atmosphere. The following lists of species probably give only a small 

 proportion of those inhabiting the county. 



CECIDOMYID^ 



The Gall Gnats of the county have not yet been studied, and although many species 

 have been collected and the galls of many more observed, tiie names of the species have not 

 been determined. 



MYCETOPHILID^ 



The Fungus Gnats also have been but little worked out. The following very meagre 

 list contains all that have as yet been identified. 



Sciara praecox, Mg. Lasiosoma lutcum, Mcq. Macrocera centralis, Mg. 



Mycetophila punctata, Mg. — hirtum, Mg. — stigma, Curt. 



— signata, Mg. Sciophila ornata, Mg. Bolitophila fusca, Mg. 



— cingulum, Mg. Macrocera fasciata, Mg. — cinerea, Mg. 

 Glaphyroptera fascipennis, Mg. — lutca, Mg. 



BIBIONIDiE 



Several of this family arc common throughout the county, especially the Fever Fly, and 

 the black, heavy-looking St. Mark's F'ly. Its red-legged cousin is not uncommon in the 

 upper dales, and the smaller St. John's Fly and its woolly relative are generally to be found 

 near wooded streams. This county is the only recorded locality for D. Jcmoratus. 



Scatopsc notata, L. Dilophus fcmoratus, Mg. Bibio nigrivcntris, Hal. 



— brcvicornis, Mg. Bibio pomona:, F. — lanigcr, Mg. 

 Dilophus fcbrilis, L. — marci, L. — johannis, L. 



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