554 Notes in 1887 upon lepidopterous larve, ce. 
small size of the leaves of the former small species, and 
its habit of creeping along the ground, renders it a less 
efficient protective back-ground for a very large larva, 
than the brown earth itself. Accordingly, we find that 
the larve are green in the early stages, when they are 
comparatively small, but become brown in later: stages. 
But in the Canary Islands and Madeira the conditions 
are different in that there are many species of Convolvulus, 
including several large-leaved forms, which do not, as a 
rule, creep along the ground, and which would make a 
far more continuous back-ground of green. Thus, in 
Madeira, Dr. Grabham informs me that the species very 
commonly feeds upon the Sweet Potato (Batata edulis)— 
a large-leaved Convolvulus. Again, the specimens of the 
moth which were shown to me in the Canaries were far 
smaller than those found in Europe, being, in fact, 
smaller than S. ligustri. In Madeira, also, Dr. Grabham 
showed me a living pupa which had been obtained from 
a wild larva which had been found when full-fed, and 
which was probably therefore of normal size. The pupa 
was very small for this species, and, I believe, smaller 
than that of S. ligustri. Hence the smaller size of the 
mature larva in these islands, and the more efficient 
back-ground afforded by the food-plants, cause the green 
varieties to gain more protection than the brown ones, 
and we therefore see that the former predominate. 
‘Such cases help us to understand the value of di- 
morphism, quite irrespective of its obvious use when the 
species possesses the power of variable colour-relation to 
the surroundings. 
The red spots and coloured borders in Sphingide.— 
Although it seems probable that the red spots are con- 
nected with the origin of coloured borders in this species, 
I do not yet see sufficient reason for the belief that these 
spots are on the way to become borders in the larve of 
Smerinthus, although the observation appears to tend in 
this direction. I believe that a careful investigation of 
the ontogeny of the larve of the genus Sesia is greatly 
wanted, and would help to throw light upon this and many 
other points. During the past summer, the materials for 
such an investigation were supplied me by George Tate, 
of Lyndhurst, but the press of other work prevented me 
from doing more than enough to lead to the opinion 
expressed above. I hope to be able to work at these 
species next year, if larve are still obtainable. 
