MELANISM AND MELANOCHROISM. 31 



very readily accept an already prepared tubular hollow, or will 

 perform all the work of excavating one for itself in rotten wood 

 or in the pith of a piece of elder twig, and in this case closes the 

 opening with the top of the cocoon. In default of a more suit- 

 able nidus it will go down into sawdust or even earth, forming 

 an ordinary cocoon of silk and the surrounding material. 



I have already referred to the fact that on one occasion half 

 of a certain brood emerged in August as an autumnal brood, 

 in time enough for a second brood to have occurred, but that 

 on no other occasion among hundreds of moths has an 

 autumnal specimen shown itself. This shows that it is very 

 unsafe in the matter of habits of this sort to regard as invari- 

 able in a species, any habit, which we may have found to be so, 

 in even a very large experience. 



This consideration prevents my saying that tridens never 

 has four-moult larvae, so frequent in some species, but I have 

 never detected one. 



Tridens occurs here at precisely the same seasons, and in 

 precisely the same places as psi. Wherein they differ in habit, 

 why there is room for the two species, why the one does not 

 displace the other, are matters on which I have still everything 

 to learn. Tridens like psi, will eat almost anything arboreal, 

 but I think it has a closer relation to rosaceous plants than 

 psi, especially fruit trees, and is perhaps commonest here in 

 pear orchards ; whilst psi is at least equally at home on forest 

 trees, and may be met with on oak, birch, etc., on which I 

 never happen to have taken tridens. I have a suspicion that 

 the fine pink tinge that has characterised some of my broods, 

 and which occurs in several Acronyctas as a variety, is here 

 related to cherry as a food, but I have instituted no special 

 experiments to test the point. 



{To be continued^ 



MELANISM AND MELANOCHROISM IN BRITISH 

 LEPIDOPTERA. 



By J. W. TUTT, F.E.S. 



{Continued from page 7.) 



Although not directly bearing on British lepidoptera, I 

 referred {Entomologisf s Record, etc., vol. i., pp. 122-125) 

 to an article by Mr. W. W. Smith, of Ashburton, New Zealand, 

 *' On the Variation oi Argyrophinga antipodum,'' to show that 

 my theory of excessive moisture producing melanism, and vice 



