The Book of the Fly / A nature study of the house-fly and its kin, the fly plague and a cure

by George Hurlstone Hardy

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.

A, III, the Frons is the forehead between the eyes; it contains (1) the Frontal Stripe; (2) the Frontal Orbits at the sides of the frontal stripe; (3) the Frontal Lunule (plate VII, 5) a crescent immediately above the antennæ. The Bristles hereabouts are (4) one pair of Frontal; a row, or rows of (5) Fronto-orbital; and (6) Lower Fronto-orbital. The (7) Eye Margin is a narrow, often glistening, white line close to the eye.

A, IV, Antennæ, jointed processes springing from between the eyes just below the frons; those with numerous joints are illustrated in plate II, others in plate III. The Frontal Suture in the middle of the face is a little pit in which short antennæ often lie close together. The (1) Basal Joints are the two next the head; (2) the Flagellum, all the joints, when numerous, taken together; (3) the First Joint is next the head; (4) the Second Joint; (5) the third Joint (plate III, 1-9) is sometimes ringed; (6) the Arista, or Seta, is a plume, spine, or bristle springing from the third joint at some point of its upper surface between the base and the tip.

A, V, the Face is the region above the so-called mouth and below the antennæ; the ridges bounding the face on each side are (1) the Facialia; here are (2) the Facial Bristles; (3) the Mystax (pl. VI, fig. 28) is peculiar.

A, VI, the Cheeks, spaces at the sides between A, II and A, V (I).

A, VII, the Jowls, parts below A, VI and the so-called mouth.

A, VIII, the Mouth, more or less of a cavity into which (3) the Proboscis (the jointed sucking trunk) can be sometimes partly withdrawn; the proboscis has a basal joint called the Rostrum (a snout); the other joint is called the Haustellum (a pump) and has the tip variously adapted as for mere surface suction, or for deep insertion, or for piercing. (1) the Peristome is the region surrounding the mouth; (2) the Vibrissæ are strong bristles close to the sides of the mouth, or A, V (I); (4) the Palpi, two feelers (or perhaps smelling organs) attached to the proboscis.

A, IX, the Back of the Head; here (I) Post-orbital Bristles are sometimes found, that is to say, behind the eyes, A, II.

B = the Thorax, the middle portion of the fly bearing the organs of locomotion.

B, I, the Dorsum. The diagram on plate VI, fig. 40 illustrates the upper surface of this region; this part is bounded in front by (a) the Neck; behind by (b) the Scutellar Suture (15) or Seam; at the sides by (c) the Dorso-pleural Sutures (9-9) running from the front corners to the front of the Wing Bases; by (d) the Wing Bases (10-10); and by (e) the Scutellar Bridges, which are ridges (11-11) running with right and left inclines to the root of (6) the Scutellum. The Dorsum is crossed by (8) the Dorsal Suture, behind which are the Alar Regions (5-5); here on each side is a ridge (12-12) the Alar Frenum; rows of minute bristles on the centre are termed Acrostichal.

B, II, the Sides, or Pleuræ, specified separately in connection with—

B, III, the Breast, or Sternum; (1) the Prothorax is below the shoulder and above the fore-leg; (2) the Meso-pleura is contiguous to the prothorax and the shoulder; here in the upper front corner is the "Stigma," a prominent respiratory orifice, below which the large Stigmatical Bristle may be found; the (3) Ptero-pleura is below the wings and behind the meso-pleura; (4) the Meta-pleura is "a more or less tubercular piece below the region between the root of the wing and the haltere"; (5) the Sterno-pleura is above the middle leg and below the Sterno-pleural Suture, where it bounds the meso-pleura; (6) the Hypo-pleura is behind the sterno-pleura and above the hind leg.

B, IV, the Meta-Notum is the part of the thorax behind and beneath B, I (6), the scutellum.

C = Appendages of the thorax.

C, I, Fore-legs, Mid-legs, and Hind-legs; every leg has nine joints [particularised illustrations on plate VII]; (1) Coxæ are the joints attached to the body; (2) Trochanters very small and inconspicuous; (3) Femora or Thighs; (4) Tibiæ or Shins; (5) First Tarsal Joint or Metatarsus; (6) Second Tarsal Joint; (7) Third; (8) Fourth; (9) Fifth Tarsal Joint; (10) the Knees are where the Thighs and Shins join; (11) Claws, Foot-pads, and Empodium are appendages of the fifth tarsal joint.

C, II, Wings [see Table of wing-cells and veins]; the quarters of the wing are the Fore and the Hind Basal Regions and the Fore and the Hind Apical Regions. The Stigma is a thickened portion of the wing at the middle of the fore margin.

C, III, the Halteres.

C, IV, Squamæ are scale-like appendages beneath the wings and above the halteres; they seem to have some attachment to the roots of the wings; a small inner lobe is called the antisquama, but it is a feature not of much use in classifying and differentiating species.

D = the Abdomen has numerous ringed sections; in the Sub-order, Cyclorrhapha in eight segments, but commonly divided into four or five conspicuous segments and three or four more smaller, less visible, and much modified in the sexual terminal segments.

D, I, the first abdominal segment is the Basal Segment.

D, II, the last of those more visible is the Anal Segment or Anus.

D, III, the abdominal termination, see plate VI, fig. 17.

D, IV, the chief segments consist each of an Upper Plate joined to an Under Plate by Membranous Sides, often concealed.

D, V, Abdominal Bristles, see plate VI, fig. 41.

E = Bristles, Hairs, etc.; fine short furry hairs are called Pubescence; "Hairs" are longer and stronger; Bristles are still stronger; but a very thick bristle is called a Spine, if on the costa, and a Spur, if on the leg; the larger bristles on B or on D are called Macrochætæ.

F = Stripes and Bands; a long marking, when parallel (or nearly so) to the major axis of the body, leg, or wing, is called a Stripe; when lying at right angles (or nearly so) it is called a Band. For "frontal stripe" see A, III (1).

O = Cells of the wing [see the following Table]; the rib-like nervures are termed Veins; these divide the area of the wing into more or less twelve compartments called Cells or Areolets.

V = Longitudinal Veins [see the following Table]; two groupings within the margin can be recognised; the principal veins of the Fore Region are numbered, 1, 2, and 3, whilst those of the Hind Region are numbered, 4, 5, 6 and 7 respectively; some have branches, a, b, c, etc., when sections (separately referred to) may have index numerals attached.

X = Cross-Veins [see the following Table]; one very significant X-vein termed X, 4 (or the Discal X) in the middle of the wing connects the longitudinal V, 4 to the V, 3, which are thus to be identified even in very abnormal patterns.

The cross-veins and cells are symbolised by having attached to the letters X and O respectively the indicative and qualifying figures and letters belonging to the V upon which they rest, that is to say, the V (or part of V) which is the lower boundary.