214 SECOND REPORT OF THE STATE ENTOMOLOGIST. 



and many of which seem ahnost to serve no higher purpose than that of 

 ornamentation. Yet it is reasonable to beheve that most of these differ- 

 ences have their use in the economy of nature, and that they aid in the 

 continuance of the species. 



Among such minor antigenetical features may be mentioned, in the 

 Lepidoptera, the usually more angulated wings of the male; the simple 

 frenulum of the most of the male Heterocera in contrast with the com- 

 pound one in the female ; the hairy anterior legs of Grapia and Vanessa in 

 the Nymphalidce ; the long hairs between the costal and subcostal nerv- 

 ures, above the cell of the hind wings of Argynfii's, appearing when dis- 

 played in the cabinet, like a long fringe to the inner margin of the front 

 wings ; the incrassated, black, scale-patch upon the middle of vein 2 (the 

 1st median nervule) of the secondaries of Datiais ; the ovoid discal spot 

 on the front wings of many of the Theclince : in the Hesperidce, the re- 

 flexed costal margin in most of the Nisoniades^ Eudanms and Pyrgus, and 

 the tibial epiphysis"^ of the anterior legs in all but one of our genera; 

 the transverse discoidal stigma on the primaries of most of the species 

 of Pa7nphila ; the beautiful and peculiar microscopic (often concealed) 

 scales, or androconia, of many of the butterflies; the usually concealed- 

 pair of extensile anal appendages found b}^ Fritz Miiller and others in 

 certain Glaticopida;^ Bo7nbycidcr^ Noctiiidcc and in a Danais,\ — each of these 

 several characters indicating the male sex. Features equally interesting, 

 and alike serving no purpose so far as known, might be mentioned in each 

 of the orders of insects. 



In the earlier stages of insects (egg and larval), sexual features, as would 

 naturally be expected, are less numerous and less conspicuous. They 

 rarely occur in the first stage — that of the &^^, or more properly, they 

 have not, in many instances, been recognized by us.j 



It was for a long time believed that in the larva of one of our Sphing- 

 idce not unfrequently met with — Thyreus Abbot ii — the sex was so clearly 

 indicated by difference in color and pattern that it could be told at a 

 glance. Of the two greatly differing forms, the one marked with a series 

 of large yellow-green patches on the dorsum extending half-way down 

 the sides, and with another row of smaller subtriangular similarly colored 

 spots resting on the prolegs, was described by Clemens as the male ; the 

 female being reddish brown throughout, with a dark brown subdorsal 

 stripe and numerous short broken striae. § This sexual determination of 



*Gueiiee: Hist. Nat. Ins., 1852 — Lepid., v. — Noct., i, p. xxxv. — Speyer: in Canad. 

 Entomol., 1878, v. 10, p. 124. Edwards' Catal. Lep. Amer., 1877, p. 64. 



t Fritz Midler : Nature, 11 June, 1874, v. 10, p. 102 (Psyche, Mar.-Apr. [9 July], 1877, v. 

 2, p. 24). Morrison: Psyche [9J, Oct. 1874, v. 1, pp. 21-22. Siewers : Canadian Entomolo- 

 gist, Mch. 1879, V. 11. pp. 47-48, fig. 12. Stretch: Papilio, Feb., 1883, v. 3, pp. 41-42, fig. 



X lu Phylloxei'a, the eggs which are to produce males and females may be known by their 

 difference in size. See Riley's Annual Reports of the State Entomologist of Missouri : fith, 

 p. 41 ; 7th, pp. 92-98; 8th, p. 158. 



§ Two colored figures of the larvae in my possession, made by Dr. Clemens, show the 

 sexes the reverse 'of this — the green-spotted one marked as $ , being much the larger of 

 the two. 



