INTRODUCTION. V 



of which fly freely during the day, whilst the females remain hidden. 

 It therefore becomes necessary for the male to have some special 

 means to detect and find out the hidden female before his flight is 

 over so that copulation may take place. If we examine the two sexes 

 of these species we are at once struck with the fact that the antennae 

 of the male are covered with strongly developed pectinations, and 

 that those of the female are comparatively simple. In TORTRICES which 

 fly during the daylight, and in which the female is comparatively 

 inactive and retired, we find the same character highly developed in 

 the male. Examples that occur to me are Amphisa prodromana, 

 Ptycholoma lecheana, Clepsis rusticana, Batodes augustiorana, Grapho- 

 litha obtusana, Stigmonota perlepidana, Catoptria ulicetana, Tortricodes 

 hyemana, and many others may be mentioned, whilst of species which 

 fly at dusk and assemble freely Caberd pusaria, C. exanthemata, lodis 

 vernaria, Cheimatobia brumata, Aspilates gilvaria, A. citraria and A. 

 strigillaria, Amphidasys prodromarta, Stauropus fagi, Spilosoma mendica, 

 the Noctuid genera Pachnobia, Tceniocampa, &c.> at once occur to my 

 mind. Here then is a distinct development of a special organ associ- 

 ated with a special habit of the species, to wit, the pectinated antenna 

 of the male, associated with an ability of the male to seek out and find 

 the female when more or less hidden. When these facts first came to 

 light it was generally assumed that the antennae enabled the male to 

 find the female by increasing his power of vision, but it is well known 

 that the male frequently retains the power even when the female is 

 completely hidden in a box &c., and I have known the male to fly 

 repeatedly to the spot where a female has been confined. It would 

 appear, therefore, that the male is most probably guided by scent and 

 that the antennas are specially devised for the reception of an attrac- 

 tive odour given off by the female. It is remarkable that where both 

 species are equally active, and the sexes fly freely together in the 

 daytime, the antennae are never specially developed, at least not to my 

 knowledge, and that in such cases the " secondary sexual characters," 

 where such exist, are generally connected with the colour, markings, 

 etc., of the wings. For example, both sexes of the butterflies fly freely 

 together and there is no special antennal development, so also do the 

 species in the genus Zygcena, and yet in the allied genus Ino, where the 

 females remain resting on the grass stems etc, whilst the males buzz 

 or fly about, the modification in the antennas at once takes place and 

 those of the males become strongly ciliated. In some species, where 

 the ciliations in the male are slight, the antennae of the female are 

 generally quite filamentous, perfectly simple and unci Hated ; but when 

 the pectinations in the male are decidedly well-developed and strongly 

 pectinated, the female also has traces of the ciliations or pectinations. 

 It must be remembered, too, that it is only in those species in which 

 both sexes have simple antennae that the sexes conform to each other 

 in this respect, and it, .therefore, would appear to be a fair deduction 

 that the antennae of lepidoptera were originally simple and that the 

 pectinated character has been acquired owing to the actual necessity 

 of the development of a sense by means of which the males shall find 

 the females. Mr. Poulton, in his paper ' On the morphology of the 

 Lepidoperous pupae,' says that the female had them and lost them, 

 but it is more difficult to suppose that the female should have had 



