1887.] VALUE OF COLOUR AND MARKINGS IN INSECTS. 197 



class, although one cannot be sure that there is not some smell, 

 given off from the general surface of the body. It will be shown that 

 in some cases it is even likely that larvae may be protected by their 

 reputation for being indigestible. Again, the larvae may be disliked 

 because of the possession of irritating hairs, as in the case of Porthesia 

 aurifiua, in which the effects of tl;e hairs are almost immediate and 

 intensely irritating (to man, and evidently to lizards &c.) ; or as in 

 other hairy larvae which cause irritation after longer contact (e. g. 

 Odonestis potntorio, from my own experience after long handling, 

 and, as I liear from others, with Lasiocampa j-ubi and L. quercus 

 &c.) ; but there is no doubt that the effects upon the delicate skin of 

 the mouth would be much more rapid in all cases. We also see that 

 more than one unpleasant attribute may be present in a single larva, 

 as in the case of P. aurijlua, &c. 



Just as there may be many ways in which a larva may be un- 

 pleasant to its foes, there are many ways by which it may be rendered 

 conspicuous, some of which have been suggested since Wallace's 

 original hypothesis. Tlius a larva may be conspicuous from its 

 startling coloration (e. g. P. avrijliia or A. grossniariata), or because 

 it freely exfioses itself, while its colours, sltiiough sober, do not har- 

 monize with its fbod-|)lant (e. g. O. potntoriaon grass, or B. rubi on 

 heatliei ). Again, it mav become conspicuous by living in companies, 

 in which case the individuals may be brightly coloured (e. g. C. neu- 

 strid, E. jacobcefp, P. bucephala, &c.) ; or may be sober-coloured, 

 but strongly Cdulrasted \\\\\\ tiie food-plant {e.g. the dark larvae of 

 Vanessa io or V. urtirce. freely exposed in companies on the tops of 

 nettles). It is obviously of less importance for the gregarious species 

 to be as conspicuiiu,-ly coloured as the isolated larvae, because the 

 numbers add greatly to the efficiency of comparatively sober colours. 

 This explanation ot the use of the gregarious habit in many species 

 was made by Fritz Miiller in ' Kosnios,' Dec. 1877, and an abstract 

 of the paper was connnunicated to the Entomological Society of 

 London by Professor Meldola (see Proc. 1>78, pp. vi & vii). The 

 descriptions of appearance in all the tables nre principally taken 

 from Newman's works, tlie habits being chiefly described from my 

 own experience. Prof. Westwood has most kiiidlv assisted me in the 

 search for the names of many of the s-pecies employed in the experi- 

 ments. (See Table I., pp. VJ^-20'i.) 



A second small group of larvae must be tabulated separately, i. e. 

 those which take advantage of two methods of |)rotection which at 

 first sight appear to be mutually exclusive — the method of protective 

 resemblance and that of a conspicuous appearance, warning of 

 unpleasant attributes. Such larvae are ajit to pass unnoticed because 

 of tiie harmony between tiieir colours and markings and the artistic 

 effect ot their surroundings ; but if discovered, or even if an enemy 

 approach so that there is danger of their being discovered, the 

 protective attitude is instantly changed for one which renders the 

 larva conspicuous and warns the enemy of the presence of unpleasant 

 attributes (taste or smell), or alarms it by the resemblance of tlie 

 new appearance to some object of terror. These facts may even be 



