1886.] Larva of Smerinthus ocellatus and its Food-plants. 139- 



Out of a large number of larvae which hatched at the beginning of 

 July, 1885, a very small proportion lived until they were old enough 

 to be of use in the present investigation. A careful examination of 

 the survivors was made on August 12th, with the following results: — 



1. Pyrus Mains (var. acerba). — Five larvae (including one which was 

 found after escaping, and which almost certainly belonged to this lot) 

 were hatched on July 2nd, and now four were well in the last stage and 

 one was changing its last skin. All five were extreme whitish varieties. 

 Eventually all these larvae died, but their colour was unchanged, and 

 they were sufficiently advanced to warrant the conclusion that no 

 further alteration would have taken place. 



2. Populus tremula, Sfc. — One larva, hatched July 2nd, was now 

 (August 12th) changing its skin for the last time and seemed to be a 

 whitish variety. By August 20th it was well in the last stage and an 

 intermediate variety, and without further change on August 27th, 

 when it was nearly full-fed (ceasing to feed : n a day or two). After 

 the first fortnight the larva was fed upon a somewhat similar species 

 of poplar, which I have not yet been able to name with certainty. 



3. Salix babylonica. — One larva (hatched July 3rd) had now 

 entered upon the last stage, and seemed to be well on the yellowish 

 side of an intermediate variety. This description especially applied 

 to the back, but there was a blueness about the ventral surface and 

 lower part of the sides which is never seen in a true yellowish variety. 

 On August 20th the larva was still on the yellowish side of inter- 

 mediate, but not to such an extent as that seen in larvae of Series III, 

 which had been fed upon the same plant. Later, the larva became 

 less yellow, so that by August 27th it was distinctly intermediate, 

 and remained without further change until September 3rd, when it 

 ceased feeding. 



4. Salix amygdalina, July 4<th — 13^, 8. triandra, July Y&th — \Mh, 

 and 8. rubra, July 14ith, onwards. — One larva (hatched July 4th — 5th) 

 was changing its last skin and apparently whitish. Another larva 

 had died at the beginning of the last stage, and was also whitish. 

 The former was dead by August 20th, so that no results were ob- 

 tained from these larvae, except the fact that the tendencies of the 

 food-plants (towards producing the yellowish varieties) had evi- 

 dently been largely counteracted in these larvae. This larva is after- 

 wards described as if fed upon 8. rubra, for the leaves were selected 

 so as to be similar to those of this tree in their effects. 



The effects of hereditary influence are certainly seen in the larvae of 

 this series. The parent larvae were extreme white varieties, and 

 belonged to a group which evidently inherited a very strong tendency 

 in this direction, as was shown by the comparatively slight effect that 

 followed the use of foods which most powerfully tend to produce 

 yellow varieties. It is certain that more dependence can bo placed 



