1886.] Larva of Smerinthus ocellatus and its Food-plants. 165 



with white muslin, which probably, therefore, produces some slight 

 effect on the larvae. Again the larvae in the field are probably 

 affected by the amount of light, and especially direct sunlight, 

 which must brighten the colours of their environment. I have 

 commonly found them on S. rubra (as in the other trees) upon 

 the higher younger branches standing out from the trees, and espe- 

 cially during the past summer upon twigs that have been allowed 

 to grow out from the tops of hedgerow sallows ; and I have also 

 noticed that they are better protected in these strong lights because 

 of the brightness of their own colour than in the shadows of the 

 lower and more crowded leaves. The bred larvae have never been 

 so freely exposed to light, and although the small leaves of the food- 

 plant do not become much disarranged (probably hardly any effect 

 would be produced if they were), yet the crowding certainly helps to 

 shade the leaves and to diminish the brightness of their colours. 

 (Daring the past summer I have kept the 4arvae under a north 

 window to protect them as far as possible from the excessive heat.) 

 It is very probable that some of the difference is to be explained in 

 this way, but most of it is no doubt due to the hereditary tendencies 

 of my bred larvae, which were always towards white, while this ten- 

 dency is probably less common than the other by the banks of streams 

 (see former paper, p. 310). It will be very interesting in future 

 experiments to breed the larvae under yellow and under white glass. 

 Next year I hope to be able to make such experiments. 



7. The Whole of the Evidence Summarised. 



I have arranged all the results hitherto obtained in a table which is 

 printed below. The only important omission is the hereditary tendency 

 of the bred larvae, and this would have rendered the table too compli- 

 cated, for there were four different series in 1885. It will, however, 

 be remembered that all the larvae bred in 1884 tended strongly towards 

 white, while nearly all of them in 1885 possessed the same tendency in a 

 slightly modified form. All the numbers without reference marks refer 

 to my own observations or experiments conducted at Oxford ; while 

 special marks call attention to the work of other observers, or to my 

 own work in other localities. The 204 instances given below comprise 

 all the cases in which the colour of the larva and the name of the 

 food-plant have been noted, either in breeding oi in field observations. 



Only in the case of the white varieties captured upon ordinary 

 apple have I ventured to allude to the larvae under the vague term 

 "very common," because such has been my experience and that of 

 other observers, although no list of instances has been kept, and 

 therefore no number can be quoted. Had I left the space blank it 

 would have conveyed an entirely wrong impression of a very general 

 experience. It must be understood that in the following descriptions 



VOL. XL. H 



