1907.] 31 



PROaRESSIVE MELANISM : 



FURTHER NOTES ON HASTULA SYERANA, Mill. 



SY T. A. CHAPMAN, M.D., F.Z.S. 



{Continued from Vol. XLII, p. 246). 



Plate I. 



One of the interesting points that arise from my 190G experience 

 with Hastula hyerana concerns the larva. My observations on the 

 larvas at Hyeres in 1904- and in Sicily in 1905, went to show great 

 differences in the larval economy in the two habitats. I correlated 

 this with the very different habits of its food-plant at the two places. 

 Therein, I believe, I was quite right. In 1906, however, I found that 

 both the plant and the larva at Hyeres were less markedly of the 

 Hyeres habit observed in 1901, and partook in some degree of the 

 Sicilian peculiarities noted in 1905. It follows of course that I was 

 wrong in supposing that the differences were racial as between the 

 hyerana at Hyeres and that in Sicily. The conclusion the 1906 facts 

 point to is, that the larval habits are probably very nearly the same 

 at both places, and are variable from year to year according to the 

 luxuriance or otherwise of its food-plant. 



It would seem that in 1904 I hit upon a year when the Asphodel 

 grew very rankly at Hyeres, and on precisely opposite conditions at 

 Taormina in 1905. At Taormina the preceding winter had been un- 

 usually severe, there having been frost intense enough to grievously 

 damage the lemon trees and in places to kill the Opuntias, so that, 

 though I do not know what is the normal aspect of Asphodel at Taor- 

 mina, its wretched condition in many places in 1905 may not have 

 been an ordinary one, but due to the plants having made less growth 

 than usual through the winter. 



However this may be, the Asphodel was not so luxuriant at Hyeres 

 in 1906 as in 1904 ; large plants conspicuously damaged by the pre- 

 sence of ten to twenty larvae of H. hyerana were not seen, single 

 larvae were common, and three or four to a plant was a maximum 

 rarely exceeded, and indeed infrequent. 



When there was only one larva to a plant the effect was incon- 

 spicuous, although the presence of the larva was almost always evident 

 on a careful look at the plant, and it was quite unnecessary to handle 

 it. A majority* of the plants flowered freely, and it was very com- 

 mon to find the solitary larva that the plant afforded burrowing 

 in the flower-head, which consequently showed a good deal of de- 

 formity when sufficiently advanced. 



