156 MR. R. MELDOLA ON VARIABLE PROTECTIVE [Feb. 4, 



long ago observed that the larva of Bryophila algce varied in colour 

 according to the nature of its food-plant, being yellow when feeding 

 on Lichen juniperinus, and grey when on L. saxatilis. Dr. Moller 

 in 1867 published a paper containing a great number of observa- 

 tions on the influence exerted by external conditions upon insects*. 

 Two of these, which belong actually to our present class, I will here 

 quote. 



The ground-colour of the larva of Cucullia tanaceti is white 

 when this insect is feeding on the leaves of the mugwort {Artemisia 

 vulgaris) or tansy (Tanacetum vulgare), but changes to a yellow 

 when it confines itself to the flowers of the latter. The larva of 

 Chesias spartiata is stated by Koch to present two varieties— one 

 of a green colour, that feeds on the leaves of broom (Spartium scopa- 

 rium), and another of a yellow colour, that feeds on the flowers of 

 that plant. This observation has been subsequently confirmed by 

 Mr. William Buckler f. The larva of Cleora lichenaria, which is 

 well known to be a wonderful case of adaptation to the lichen on 

 which it feeds, is stated by Dr. Knaggs % to vary in depth of colour 

 according as it occurs on light- or dark-coloured lichen. Many 

 polyphagous caterpillars of the genus Eupithecia tend to assume 

 the colour of the flower on which they are feeding : this is parti- 

 cularly to be observed in E. absynthiata ; and, in a recently pub- 

 lished description of the larva of E. pimpinellata, which feeds on 

 the seeds of Pimpinella magna and P. saxifraga, it is stated that 

 " the colour of the larva seems to assimilate with the seeds — green 

 ones upon green unripe seeds, and the red ones upon the purple 

 ripe seeds" §. I have likewise observed a similar tendency in the 

 larva of Mamestra persicarice to partake of the tint of the leaf on 

 which it was feeding. 



The experiments of Mr. T. W. Wood || and others seem to esta- 

 blish the fact that under certain conditions the pupae of Lepidoptera 

 tend to assume the colour of the surface on which the larva made 

 its final change. Mr. Wood has observed, for instance, that a pupa 

 of Vanessa polychloros was coloured like a dead leaf when among 

 foliage, while a specimen from a wall was mottled grey. I have 

 observed a similar fact with respect to the pupse of Synchloe bras- 

 sicce and S. rapce, specimens from a black fence being generally 

 darker than those found on walls. The particular conditions under 

 which this photographic sensitiveness is acquired have not yet been 

 fully investigated ; but such a tendency in a state of nature cannot 

 but act beneficially towards the species by affording concealment ; 

 I therefore propose to include such cases in the class now under 

 consideration. 



With reference to insects in the perfect state, I am informed by 

 Mr. F. Bond that Gnopkos obscurata tends to vary in its ground- 



* Die Abliangigkeit der Insecten von ihrer TJmgebung. 



t Entora. Monthly Mag. April 1871, p. 261. 



\ Lepidopterist's Guide, new ed. p. 47. 



§ Mr. William Prest in 'Newman's Entomologist,' Nov. 1872, p. 241. 



|| Proe. Ent. Soc. of Lond. 1867, p. xcix. j 



