LEPIDOPTERA 663 



delicate in appearance. This appearance is due both to the thinness 

 of the membrane and to the fineness of the scales with which the 

 wings are clothed. These moths occur on the borders of woods and 

 in forests, rarely in meadows and pastures. Their flight is neither 

 strong nor long sustained. Many species when at rest hold the wings 

 horizontally and scarcely overlapping ; but other species assume other 

 positions. 



In the geometrids the frenuliim is usually well-preserved, but in 

 a few it is wanting or vestigial. A striking feature of the wing-venation 

 is the fact that the basal part of the subcosta of the hind wings makes 

 a prominent bend into the humeral area of the wing and is usually 

 connected to the humeral angle by a strong cross-vein (Fig. 817). 



A monograph of the geometrid moths found in the United States 

 was published by Packard ('76). 



The superfamily Geometroidea includes two families; but one of 

 these, the Manidiidce is represented in our fauna by a single rare species. 



Family GEOMETRID.E 



In this family the antennas are not clubbed, as in the next family. 

 The other distinctive features of the Geometridse are those given 

 above in the characterization of the superfamily Geometroidea. 



There occur in our fauna representatives of six subfamilies of the 

 Geometridse; these can be separated by the following table: — ■ 



A. Eyes small and oval. p. 664 BREPHiNiE 



AA. Eyes round and usually large. 



B. Vein M2 of the hind wings vestigial, being represented merely by a fold in 

 the wing or by a non-tubular thickening (Fig. 817). p. 670. .Geometrin^ 

 BB. Vein M2 of the hind wings well-preserved. 



C. Vein M2 of the hind wings arising much nearer to vein Mi than to vein 



M3 (Fig. 820). Wings usually green, p. 665 Hemithein^e 



CC. Vein M2 of the hind wings arising nearly midway between veins Mi 



and Mj or nearer to vein Mj than to vein Mi. Wings rarely green. 



D, Veins Sc -+- Ri and Rs of the hind wings extending distinctly separate 



from each other, except that they are connected by the free part of vein 



Ri near the middle of the discal cell (Fig. 821). p. 666. . . . Larentiin/E 



DD. Veins Sc -f- Ri and Rs of the hind wings approximated or coalesced 



for a greater or less distance. 



E. Veins Sc -f Ri and Rs of the hind wings closely approximated but 

 not coalesced along the second fourth (more or less) of the discal 

 cell. With transverse rows of spines on abdominal segments. {Pal- 



cBacrita). p. 670 Geometrin^ 



EE, Veins Sc + Ri and Rs of the hind wings coalesced for a greater or 

 less distance. Abdomen without transverse rows of spines. 

 F. Veins Sc -+- Ri and Rs of the hind wings coalesced for a short 

 distance near the beginning of the second fotu-th of the discal cell, 



thence rapidly diverging (Fig. 821), p. 666 Acidaliin.^ 



FF. Veins Sc + Ri and Rs of the hind wings coalesced to or beyond 

 the middle of the discal cell (Fig. 823), or with a short fusion near 

 the end of the discal cell. 



G. Fore wings with one or two accessory cells, p. 666. . Larentiin^e 

 GG. Fore wings without an accessory cell. p. 664. . CENOCHROMiNi? 



