There is no English work sufficiently modern and comprehensive for a study of our native flies. In 1776, Moses Harris, who originated or elaborated the study of wing patterns, published his "Exposition of English Insects," in which more than 300 flies are figured and described; they have the old Linnæan classification and nomenclature, of course, and the work is scarce. All later attempts by English authors in the way of a more comprehensive student's guide book have been left incomplete. Another excellent, but expensive work, Curtis's "Genera of British Insects," contains about 250 illustrations and descriptions of flies; but most of these are rather rarities, and the amateur in search of a facile guide to the commoner objects of the country-side will be apt to be disappointed. For the sake of readers possibly eager of advancing further in the study, and in the absence of any commendable guide book, a short appendix has been added to the present work, for help in identifying more numerous species and those of many families and genera not mentioned in the foregoing pages. With the leave of the Northumberland, Durham, and Newcastle-upon-Tyne Natural History Society some valuable plates of illustrations are herewith reprinted, and explanatory notes are added, mainly from the volume of the Society's transactions for 1906, a most valuable work and compilation by the late Rev. W. J. Wingate, of Bishop Auckland. This learned entomologist has succeeded in giving a marvellously comprehensive amount of clear condensed guidance. It is a great privilege that the present booklet has been allowed to borrow from such a source of knowledge, valuable far beyond the locality of its authorship. Other illustrations which have been borrowed appear with the leave of His Majesty's Office of Works, out of Reports to the Local Government on Public Health and Medical Subjects. [Illustration: FLY CHART. PLATE I. (APPENDIX) ] APPENDIX INDEX TO TERMS AND SYMBOLS OF THE WINGATE FLY CHART, _PLATE_ I. This Index, together with the following "Table of Wing-cells and Veins," the "Glossary," and _plates_, II, III, IV, V, VI and VII, will explain the theoretical Diagram entitled The Fly Chart, illustrating characteristic features and exterior parts, by the study of which the reader may learn to differentiate all the sixty families which contain species native to Great Britain. A = the Head, comprising nine regions and parts (A, I to A, IX). A, I, the Vertex, which contains (1) the Ocellar Triangle; (2) the Ocelli; (3) the Vertical Triangle, a coloured patch surrounding the ocellar triangle; (7) the Vertical Orbit, the sides of the vertex close to the compound eyes. The Bristles hereabouts are (4) the Vertical (inner and outer); (5) the Post-vertical; and (6) the Ocellar. A, II, the Compound Eyes, large and often hairy.