58 ON PLANTS AND INSECTS. [LECT. 



low plants often go down to the ground, and turn 

 brown, those which feed on large trees or plants 

 remain on the under side of the leaves, and retain 

 their green colour. 



Thus, in Smerinthus ocellatus, which feeds on the 

 willow and sallow; S. populi, which feeds on the 

 poplar; and S. tilice, which frequents the lime, the 

 caterpillars all remain green ; while in those which 

 frequent low plants, such as the convolvulus hawk- 

 moth, which frequents the convolvulus ; Chcerocampa 

 nerii, which feeds in this country on the periwinkle ; 

 Chcerocampa celerio, Ch. elpenor, and Ch. porcellus, 

 which live on galium, most of the caterpillars turn 

 brown. There are, indeed, some caterpillars which are 

 brown, and still do not go down to the ground, as, for 

 instance, those of Aspilatis aspersaria, and indeed of 

 the Geometridce generally. These caterpillars, however, 

 as already mentioned, place themselves in peculiar 

 attitudes, which, combined with their brown colour, 

 make them look almost exactly like bits of stick or 

 dead twigs. 



The last of the five points to which I called your 

 attention was the eye-spots. In some cases, spots may 

 serve for concealment, by resembling the marks on dead 

 leaves. In Deilephila hippophae, which feeds on the 

 hippophae, or sea buckthorn, a grey-green plant, the 

 caterpillar also is a similar grey-green, and has, when 

 full grown, a single red spot on each side, which, as 

 Weismann suggests, at first sight much resembles in 

 colour and size one of the berries of hippophae. This 

 might, at first, be supposed to constitute a danger, and 

 therefore to be a disadvantage, but the seeds, though 



