242 



THE YOUNG NATUEALIST. 



such as I mentioned will fit in it, side by side, the whole can be packed in a 

 bag without trouble. 



The day we choose for our entomological outing is one neither very wet 

 nor very cold, in fact it is as fine a day as we can expect in November ; and 

 I have mostly found a fair proportion of days even in this most moist, foggy 

 and disagreeable month, on which an entomological excursion could be made 

 without very much discomfort. 



Should the weather be fairly dry — and in some years we do have a less 

 moist November than we have in others — I have found this mouth a very 

 good one for pupa digging, and perhaps a more productive one than any, 

 for underground pupae have many foes — moles are especially most destructive 

 to them, and devour them by thousands—so that even the commoner kinds 

 get scarcer when we get over Christmas ; and in some places where moles 

 abound, you may spend hours digging about the roots of trees and not find 

 a single chrysalis after all. 



We will commence operations at this willow tree, growing in a hedge. 

 First, we will search on the bark for the hard woody cocoon of the Puss moth 

 (Cerura vinula.) See, here is one, looking somewhat like half a walnut, 

 stuck in a crevice of the bark. It is fixed very tightly, and we shall need 

 our blunt, strong-bladed knife to remove it. 



Now we will lever up the sods of grass round the roots of the tree, and 

 pull them to pieces for the pupae of Tczmocampa instabilis, of which I have 

 found as many as twenty sometimes round the roots of one willow tree. Here 

 are one, two, three, four, in this one sod, and here are five more in another, 

 but you digging on the other side of the tree have not found any. " How 

 is that? " you ask, when I have found nine in two sods ? " Because I have 

 been digging on the north side of the tree and you have been searching the 

 south side." " Is then the north side of a tree the best for pupse ? " you 

 ask. "I have always found it so. Did you notice that I found the Puss 

 moth cocoon on the north side of the trunk ? I suppose it must be a wise 

 instinct which leads the caterpillar to prefer that side for its pupal change on 

 which the sun shines the least, for otherwise the rays of that luminary might 

 cause the moth to break from its pupa before its time, and at a season when 

 the cold nights would be fatal to it. Or it may be because the north side of 

 the tree is the mossiest/' " I suppose then it is never any use to look on 

 any other side ? " " No, I will not assert that. I only say that my experi- 

 ence is that the north side is generally the most productive. I do not say I 

 never find pupae on the other sides of the tree, although I seldom do." 



But now having carefully pulled the sods to pieces, and thoroughly exam- 

 ned them for instabilis pupae, and searched immediately beneath them for 



