450 Mr. C. Scliaposchnikow oh the Red Colour 



eyes upon the bright object, as tlie flying Catocala appears to 

 it to be. The brighter tlie effect of its colour, the more diffi- 

 cult will it be, owing to the contrast of hue, to recognize the 

 grej patch into Avhich, especially upon grey bark, tlie moth 

 converts itself at the moment of settling. Were its colours 

 wholly grey, the pursuer, fixing its gaze upon this grey 

 object, would pay most attention to its outlines and not to its 

 colour; and consequently the object would always remain 

 visible to the enemy, to wdioni the spot upon which it had 

 settled would likewise be apparent. Assuming that its 

 contrast in colour is absolutely necessary to the moth, it is 

 evident (1) that moths that have recourse to the above- 

 described mode of flight, which I would terra " distracting " 

 flight, must possess the brightest coloration, and (2) that 

 those that exhibit briglitly coloured hind wings must also 

 have a bright-coloured underside to all the wings, in order to 

 be able to give greater effect to the influence of this coloration 

 in flight. Since, moreover, the larger the moth the less is 

 the advantage that it is able to gain from its mimetic colora- 

 tion, while, on the other hand, it is all the more capable of 

 saving itself by means of its powers of flight, it follows from 

 these two hypotheses that the largest species of Catocala 

 must also show the brightest colours. The red Catocala 

 chiefly inhabits woods composed of the various deciduous 

 trees. In perspective a wood appears generally as a green 

 background (foliage and grass) with some light and dark 

 streaks (tree-trunks and their shadows) ; consequently as a 

 contrast of colours we have the red, which serves a comple- 

 ment of the green. And, again, it is especially in the most 

 robust representatives of their genus that this red coloration 

 must display itself. As a colour -contrast to the light and dark 

 stripes in the wood there appear in addition the black- and 

 white-banded undersides of the fore and hind wings of our 

 moth, which cause the latter to be easily visible in the light 

 as well as in the dark interspaces among the trees. 



AVith this appearance of species of Catocala with red hind 

 wings is also connected their geographical distribution. 

 Their predominance in the northern half of Europe is espe- 

 cially characteristic, for among all the species of Catocala 

 in this region we find only two which show no red. The 

 conditions presented to them in the area in question are the 

 following : — the forests are not so dense as in warmer lands, 

 so that usually sufficient space remains to allow the moth to 

 make use of its powers of flight ; moreover, a perspective is 

 produced which, in accordance with the hypothesis expressed 

 above, enables the moth to bring its corresponding coloration 



