VARIATION. 279 



DESCRIPTION OF PLATE IV.— {Continued:) 



Fig. 2d. — Pupa oi Acrouycta {Citspidta) aceris, lateral view of anal armature, X 8 dm. 



Fig. 3a. — Moina 07-ion, pupa, ventral view of anal armature, X 8 diam. 



Fig. 3b. ,, ,, dorsal ,, ,, ,, 



Fig. 3c. ,, ,, lateral view of anal armature, x 8 diam. 



Fig. 4. — Acronycta {Bisulcia) ligiistri, lateral view of anal armature, X 8 diam. 



Fig. 5- — Diloba cxritleocephala, dorso-lateral view of anal armature, X 8 diam. 



^^ARIATION. 



Seasonal Variation of Larv/E. — I have noticed that some larvie 

 alter the colour of their coats according to the season of the year. 

 Notodoiita dictcea affords a striking example of this, as one seldom or 

 ne\»€r gets a green larvae in October, they are all brown, and vice versa 

 in August. These two forms have different habits — the green form 

 chooses the edge of a leaf for its resting-place, while the brown form 

 rests on the twigs ; a very wise provision of nature, for if it rested on 

 the leaves in the autumn it would run a great risk of being blown away. 

 When feeding it always grasps a twig with its hind claspers, and eats a 

 contiguous leaf. What a wonderful outcome of evolution is this that a 

 lowly caterpillar, a mere fcetal moth, should so adapt itself to the 

 vicissitudes of a poplar tree in autumn ! There are many wonders in 

 the evolution of species, but none it appears to me more marvellous 

 than this. N. didcea will continue eating until it is ready to shed its 

 larval skin, and does so a long time after its mode of progression 

 becomes an ungainly wobble ; and I should think in a state of nature 

 it falls off the tree when ready to pupate, like an over-ripe plum. An 

 insect with such an appetite surely requires some special adaptation to 

 prevent it pupating supperless, and nature apparently supplies the want 

 in this manner. The variation itself is, of course, protective. The 

 yellow and brown form of N. dromedarius is always that found in late 

 autumn, while earlier in the year I have occasionally met with a beautiful 

 green and pink form. Cuspidia {Acronycta) leporina has also two forms 

 of larvae : the one green with whitish hairs, the other black with yellow 

 hairs, the latter preserving the colours of the young larvse. Dr. Chapman 

 considers this variation to be geographical — the former being the 

 southern form, the latter or yellow form occurring chiefly in Scotland. 

 Here, as one might expect, I get both forms in fairly equal proportion, 

 and they are probably seasonal, I never get the yellow form in e.irly 

 autumn, but it is the commoner when the leaves begin to turn. I 

 know of two other species that exhibit this dimorphism. These are 

 Eupithecia absynthiata and E. assimilata. The bright yellow form of 

 the former is only found on those plants (I get it here from ragwort) 

 still in bloom (I have taken pink forms from tansy), while those found 

 on the seeding blossoms exhibit the V-shaped markings and are brown. 

 E. assimilata has an early green and late brownish form, also E. lariciata 

 but it is not so marked. Manie.stra brassica gets blacker and more 

 dingy as the season advances, and the brown forms of Iladena oleracea 

 and H. chenopodii :ix&morQ. common in late autumn. — Richard Freer, 

 Rugeley, Staffs. 



Smerinthus ocellatus, Variety of Larva. — Larvae of the above 



