Figures 1-2. 1, Venation of Tephrostola gramivora, a New World castniid, showing the frenulum (f) and narrow cell (c) with the quadrifid condition: four veins arising from it. 2, Venation of hindwing of Eurema hecabe (Pieridae) showing absence of frenulum and an enlarged humeral area (h).

Figures 3-7. Venation of Cossidae (3-5) and Metarbeidae (6, 7), showing the presence of the M vein stem (m) in the cell. 3, Cossus chloratus; 4, Zeuzera lineata; 5, Xyleutes lutescens; 6, Squamura kinabalua; 7, S. disciplaga.

Figure 8. Dorsal view of the head of a chalcosiine zygaenid, showing the chaetosema (c) and ocellus (o). The chaetosema (plural: chaetosemata) here covers a broad area posterior to the ocellus, the bristles arising from a ‘honeycomb' of short, broad scales. In other families, e.g. Tortricidae, the chaetosema is restricted to a small tuft of bristles just posterior to the ocellus.

9	Haustellum (coiled tongue) present; antennae often thickened; forewing radial veins often branched; usually brightly coloured. .................................................................. ZYGAENIDAE
-	Haustellum absent; antennae bipectinate; forewing radial veins arise directly from cell; small, sparsely scaled brownish species; W. Europe,  S. Africa . .................. HETEROGYNIDAE
10	Tympanum present at base of abdomen (sternites 1 + 2) .... ....... DUDGEONEIDAE
-	Tympanum absent 11
11	Forewing with only one strong anal vein, though there may be a weak vein CuP or a fold in its position (e.g. Fig. 6) .. ..................... .12
-	Forewing with vein CuP moderate to strong: two anal veins (e.g. Figs. 3-5) .............. 13
12	Hindwing with posterior angle of cell with three veins arising from it in closely trifid formation; both wings ovoid with blotchy pattern of white or colour on black; Oriental ....... . RATARDIDAE
-	Wings narrow with hindwing venation not as above, patterning often reticulate or striate ... METARBELIDAE
13	M bifurcate within cell on both wings or cell divided into three or more subcells (e.g. Figs. 3-5); abdomen extends well beyond hindwings; forewings tend to be elongate, narrow .................. 14
-	M bifurcate within cell of only one or neither wing; abdomen usually does not extend far beyond hindwings if at all; wings not abnormally elongate, often deep .. ...
14	Head with roughened hair-scales; antennae usually bipectinate to apex; wings sparsely scaled, usually black or brown, often transparent; adult never larger than 40mm span; larva case-bearing .. .. .......... Psychidae (part) (microlepidoptera)
-	Head neatly scaled;  antennae often pectinate only over basal half; forewings often very elongate with fine, reticulate or transversely striate patterning; adult often more than 40mm span; larva wood, stem or root boring ... ..................................... COSSIDAE
15	Wings sparsely scaled, black or brown; larva case-bearing .. ... Psychidae (part)
-	Wings otherwise: if black then densely scaled ............ 16

Figures 9-13. Venation of Limacodidae (9, 10), Megalopygidae (11, 12) and Daceridae (13). The position of vein R₅ is indicated (r). 9, Setora cupreiplaga; 10, Setothosea asigna; 11, Norape cana (forewing only); 12, Trosia punctigera; 13, Pinconia ochracea (forewing only).

16	Forewing cell divided longitudinally in three with distal veins all arising directly from it or with, at most, only one distal bifurcation; very small moths with roundedly triangular, often blackish forewings; larvae predatory on Homoptera ...... ...................... EIPYROPIDAE
-	Forewing cell only divided into two and/or distal veins branching more complexly than a single bifurcation . . ............... ..... 17
17	Forewing costa markedly concave; Sc and radial veins closely adpressed (but not fused) at cell apex; wings pale, uniform, bone colour, slightly translucent; N. Africa .... SOMABRACHYIDAE
-	Forewing costa straight or convex . ...... 18
18	Forewing veins R4 and R5 stalked independently from other radial veins (Fig. 13), which are usually also stalked, though R4 and R5 sometimes anastomose with them to produce an areole; male forelegs plumose; forewings very deep, generally yellow, cream or white; New World .................................................................................................................. DALCERIDAE
-	Forewing radials branching in a single system; male forelegs not plumose .. 19
19	Hindwing area approximately equal to that of the forewing, never less than three-quarters of the area, both wings generally deep, somewhat rounded; forewing densely and coarsely scaled; Africa ...... CHRYSOPOLOMIDAE
-	Hindwing area usually less than three-quarters of that of the forewing; forewing usually elongate-quadrate or roundly triangular, finely scaled ... .... ..... ....... ...... .  20
20	Forewing veins R2 to R5 branching from a common stalk, 2-4 arising anteriorly and 5 posteriorly (Figs. 11, 12); in a few genera 2 arises from the cell or is connate with the stalk of the rest, but 4 is still anterior; antennae usually bipectinate to apex; New World ... MEGALOPYGIDAE (part)
-	Forewing veins R3 to R5 arise from a common stalk, 3 anteriorly and 4 and 5 posteriorly (Figs. 9, 10); male antennae usually broadly bipectinate only over basal half to two thirds......................................................................................................... LIMACODIDAE*
21	Tympanum present on thorax or abdomen (Figs. 14, 15) .. ...... .22
-	Tympanum absent .......37

* The genera Aidos Hubner and Xenarchus Herrich.Schaffer, currently placed in the Megalopygidae, key out as Limacodidae on both venation and antennal characters. Semyra Walker and Prolimacodes Schaus are New World Limacodidae tending towards the Megalopygidae condition.

22	Tympanum present on metathorax (This is a difficult character with which to become familiar, and the reader is recommended to examine species such as those in the noctuoid subfamilies Stictopterinae and Plusiinae where the character is easily observed; once appreciated in these species, it will be easier to note it in others) .....................NOCTUOIDEA . ........ 23
-	Tympanum present on first, second or seventh abdominal segment .......................................... 26

Figures 14-15. Thoracic tympana and associated structures of (14) Noctuidae (Plusiinae) and (15) Arctiidae (Arctia). The body is viewed laterally with the hindwing (H) held erect, the anterior, with frenulum (f), to the right. The tympanum (t) is accompanied in 15 by the tymbal organ (ty). The counter-tympanal hood (cth) is on the first abdominal segment with the spiracle (s) anterior (14) or posterior (15) to it. Modified from original drawings by G. de Heaume.

22	Tympanum present on metathorax . NOCTUOIDEA ............. . 23
-	Tympanum present on first, second or seventh abdominal segment .......................................... 26
23	Forewing with vein M2  nearer to M3 at its base on the cell than to M1 (Figs. 16-18); tympanum directed posteriorly .. ..................................... 24
-	Vein M2 nearer M1 at base or approximately central (Figs. 19-20); abdomen long, usually extending well beyond hindwings; tympanum directed ventrally .............. ....... .. NOTODONTIDAE (including DIOPTIDAE, THAUMETOPOEIDAE, THYRETIDAE)
24	Counter-tympanal hood on abdomen post-spiracular (Fig. 14) or absent ........ NOCTUIDAE
-	Counter-tympanal hood pre-spiracular (Fig. 15) ** ................. 25

Figures 16-20. Venation of Lymantriidae (16), Arctiidae (17), Noctuidae (18) and Notodontidae (19, 20), showing position of vein M₂ (m). 16, Redoa sp.; 17, Utetheisa pulchelloides; 18, Spodoptera litura; 19, Brykia samarinda (forewing only); 20, Quadricalcarifera charistera.

25	Haustellum usually well developed (but not in some Arctiinae); base of hindwing vein Sc swollen; tymbal organ (Fig. 15) usually present (but often reduced in Ctenuchinae); abdomen never with pockets between sternites 3 and 4 .. ARCTIIDAE (incl. CTENUCHINAE, PERICOPINAE)
-	Haustellum always vestigial; base of hindwing vein Sc not swollen; tymbal organ absent; pair of finely corrugated pockets usually present on abdomen on sternite 4 (Fig. 21).. LYMANTRIIDAE

Figure 21. Corrugated pockets on sternite 4 of abdomen in Lymantriidae.

26

Hindwing with veins Rs and Sc fused or at least closely approximated within and for some distance  beyond the cell; hindwing anal veins usually three; hindwing veins M2 and M3 often arising from a common stalk; forewing never with areole (if anal veins are two or an areole is present on the forewing then choose other half of couplet) ............... Pyralidae (microlepidoptera)

-

Hindwing with veins Rs and Sc separate or sometimes approximate but seldom fused beyond cell (if so, then anal veins of hindwing two, or areole on forewing present (Fig. 22), and hindwing veins M2 and M3 arising separately from cell); in GEOMETRIDAE Sc is strongly flexed at the base (Figs. 24-28) GEOMETROIDEA ....................................................................................... 27

** The Noctuidae include a group of species referred to the Herminiinae (included also in Hypeninae) with a pre-spiracular hood; these are mostly delicate, medium-sized, brown moths with an obtusely angled, usually pale submarginal to the hindwing.

27	Tympanal organs of seventh abdominal segment; restricted to Mediterranean .. AXIIDAE
-	Tympanal organs on first or second abdominal segment (Figs. 43-45) . 28
28	Hindwing vein Sc approximating to, or joining Rs beyond the cell (Fig. 22) .. . 29
-	Hindwing vein Sc remote from Rs beyond the cell (Figs. 23-28) .... 31
29	Forewing with vein M2 basally approximate to M3 (Fig. 22); forewing often falcate (hook-tipped) or with central angle at margin. Often brightly coloured or intricately patterned ... DREPANIDAE
-	Forewing M2 nearer M1 at base, or at most midway on cross-vein between M1 and M3 uncus of male genitalia trifid (see illustrations in Holloway (1976: figs. 347 - 9)) ..................................... 30

Figures 22-23. Wing venation of Drepanidae (22) and Epiplemidae (23), showing the areole (stippled) in the former and the position (m) of vein M₂ in both (M₁ is anterior to it). 22, Tridrepana fulvata; 23, Epiplema wilemania.

30	Forewings triangular, slightly falcate, lacking an areole; build slender; hindwing M2 roughly midway between M1 and M3 at cell; Oriental Region .................................................. CYCLIDIIDAE*
-	Forewings elongate, roughly twice as long as broad, always with an areole; build robust; hindwings with M2 much closer to M3 than to M1 at cell ............................................... THYATIRIDAE*

Figures 24-28. Wing venation of Geometridae. 24, Ozola pannosa (Oenochrominae); 25, Lophomachia semialba (Geometrinae); 26, Eois plumbacea (Larentiinae); 27, Problepsis apollinaria (Sterrhinae); 28, Semiothisa emersaria (Ennominae). Vein M₂ of the hindwing meets the cell end crossveins between the anterior and posterior angles, and is absent in Fig. 28.

31	Forewing with R5 remote from R2-4 and usually fused over the basal portion with M1 leading to two systems of branching veins distal to the cell (Fig. 23); areole absent; male with tympanal organs on tergum 2,opening posteriorly (Fig. 44) (at base of abdomen in female) . . .. 32
-	Forewing with radial veins 2-5 combined in one branching system of veins distal to the cell (e.g. Fig. 27); forewing areole often present; male and female with tympanal organs at base of abdomen on first segment Fig. 43 . GEOMETRIDAE .......................... . 33
32	Frenulum absent; hindwing usually with single tail or angle; large moths (URANIINAE) or, if moderate to small, usually white with fine fasciae and striation (MICRONIINAE) ..........................................................................................  URANIIDAE
-	Frenulum present; hindwing often with two tails or angles; small moths, spanning 20mm or less (except for the Decetia Walker group which are moderate in size and mostly lack tails) ........... EPIPLEMIDAE
33	M2 of hindwing lacking (Fig. 28) or reduced to a fold .............................. ENNOMINAE
-	M2 of hindwing strong . 34
34	Sc of hindwing anastomoses strongly with Rs within the cell (Fig. 26), or (rarely) connected with it within the cell by a cross-vein (R1) . . ... LARENTIINAE
-	Sc free (Fig. 24) or approximating to Rs basally or subbasally (Fig. 27) but rarely fusing with it . 35
35	M2 arises very much nearer M1 than M3 on hindwing (Fig. 25); the majority of species are green; uncus of male genitalia bifid or, most commonly, associated with two socii ...... GEOMETRINAE
-	M2 on hindwing arises approximately from mid-point between M1 and M3 (Figs. 22, 27) . ... 36
36	Sc on hindwing free though occasionally converging briefly with Rs or connected by a cross-vein (R1) with cell subbasally (Fig. 24); grey, or occasionally yellow, brown or white moths with few fasciae; bodies usually slender and legs long; if robust then moths large ... OENOCHROMINAE
-	Sc touches Rs over a short distance subbasally but does not fuse with it (Fig. 27); moths usually pink or pale fawn, sometimes yellowish or white, the wings often multifasciate ... STERRHINAE
* Minet (1983) has subordinated these two families to the Drepanidae.
37	Large moths (wingspan over 40mm), or, if small, forewings broad,triangular; haustellum often absent or vestigial; frenulum also often absent; ocelli and chaetosemata (Fig. 8) absent (if chaetosemata present then hindwing conspicuously tailed or antennae filiform, expanding towards apex, combined with orange and brown pattern and butterfly-like build) ......... 38
-	Small to medium-sized moths (wingspan usually under 30mm); wings, with a few exceptions, narrow, the forewing twice as long as broad or more, square-ended or lenticular in many instances; haustellum and frenulum usually present; ocelli and chaetosemata sometimes present ....................................................................................... the remaining microlepidoptera
38	Chaetosemata present ......... 39
-	Chaetosemata absent ... 40
39	Wingspan greater than 40mm; hindwing tailed, resembling species of Uraniidae; New World ...................................... .... SEMATURIDAE (part)
-	Wingspan less than 40mm; hindwing rounded or, at most, angled; build and field behaviour butterfly-like; pattern of wings orange on dark brown; Indo-Australian tropics .CALLIDULIDAE
40	Forewing (Fig. 29) veins R4 and R5 arising from a common stalk at the cell, separated from that giving rise to R2 and R3 ; M1 is usually only connate at the base of R4+5 New World MALLONOIDEA: MIMALLONIDAE
-	Forewing veins with different configuration. BOMBYCOIDEA . . 41
41	M2 arising nearer M3 than M1 in both fore- and hindwings, such that the cubitus (posterior vein of cell) appears quadrifid or four-branched (Fig. 31) . .. . 42
-	M2 arising nearer M1 than M3 in at least one pair of wings such that the cubitus appears trifid or three-branched (Fig. 30) .. .... 46
42	M1 on forewing usually stalked with R5 radial veins usually in two branching systems (Fig. 31); hindwing veins Sc and Rs share a short common stalk or anastomose, separating from the cell near the base (Fig. 31) ........ ....................... LASIOCAMPIDAE
-	M1 on forewing not stalked with R5 but usually connate at base; fore- wing radial veins in a single branching system; hindwing vein Rs separates from cell at its anterior distal angle and is not associated with Sc when not forming part of cell .. .. ................ 43

Figures 29-32. Wing venation of Mimallonidae (29), Bombycidae (30), Lasiocampidae (31), and  Brahinaeidae (part of hindwing only) (32). Veins R₅ (r) and M₁ (m) are indicated in 29 and 31. 29, Cicinnus despecta; 30, Ocinara albiceps; 31, Streblote acaciae; 32, Brahmaea hearseyi.

43	Hindwing vein Sc adjacent to, or fused with cell at base only, with no cross-vein ... 44
-	Hindwing vein Sc linked to cell by cross-vein (R1) ... . ..... 45
44	Forewing with a large areole beyond the anterior angle of the cell; Australasia ... ANTHELIDAE
-	Forewing without an areole .......... ... . EUPTEROTIDAE (part)
45	Antennae stout, often hooked at the tip, rarely distinctly bipectinate; haustellum often very long though sometimes weak; frenulum present . .... ... SPHINGIDAE
-	Antennae distinctly bipectinate, not hooked apically; haustellum weak; frenulum absent; Palaearctic . ............................. ENDROMIDAE
46	Frenulum strongly present (though reduced in female EUPTEROTIDAE) .. . 47
-	Frenulum very weak or absent . . 49
47	Haustellum strong; hindwing vein Sc connected to cell by cross-vein (R1); Australia . . . CARTHAEIDAE
-	Haustellum reduced or absent; hingwing Sc mostly not connected to cell by cross-vein . . 48
48	Medium-sized species; forewings usually falcate or forewing margin angled; markings on hindwing usually distinctly more intense along the dorsum; New World . APATELODIDAE
-	Medium to very large species; forewings rarely falcate, margins mostly rounded; hindwing markings not more intense along dorsum; wing scaling coarse; predominantly Old World .............................................................................................. EUPTEROTIDAE (part)
49	Hindwing finely folded along dorsum (Fig. 30) which is straight to concave with dark markings and fasciae more intense; Old World ................ BOMBYCIDAE
-	Hindwing not folded or with markings conspicuously darker . ... ...... ..... 50
50	Hindwing vein Sc well separate from cell and not linked to it by a cross-vein except almost basally ............................ 51
-	Hindwing vein Sc and Rs in cell closely approximate, fused or linked by R1 as a cross-vein ... 52
51	Haustellum fairly strong; male antennae bipectinate; New World . OXYTENIDAE
-	Haustellum vestigial or absent; often very large moths with hyaline patches or ocelli at the forewing or hindwing discal area; male antennae often quadripectinate .. SATURNIIDAE
52	Hindwing Sc linked to cell by cross-vein; New World .... CERCOPHANIDAE
-	Hindwing otherwise .... 53
53	Sc of hindwing approximate to distal half of cell and to Rs beyond before diverging (Fig. 32); hindwing cell short, broad, with medial veins weakly present within it; distinctive rippled pattern between postmedial and submarginal of both wings .... . BRAHMAEIDAE
-	Sc and Rs fused over much of length, separating well beyond end of cell; space lb of forewing often with prominent median line of contrasting colour . LEMONIIDAE
54	Tympanum present on thorax or abdomen ...... . 55
-	Tympanum absent . .... microlepidoptera
55	Tympanum thoracic .. . . LYMANTRIIDAE
-	Tympanum at base of abdomen . .. GEOMETRIDAE