Annual Address of V. T. Chambers, Esq. 89 



on each side of which are a few minute retrorse teeth, with their anterior 

 margins forming a cutting edge: and each abdominal segment is armed 

 on its dorsal surface with a row of microscopic thorns, pointing backward. 

 All these are useful to the pupa in making its exit partially' from the 

 cocoonet and mine, preparatory- to disclosing the imago; and the an- 

 terior half of the body having by means of this armature been pushed 

 through the opening made in the cocoonet and cuticle of the leaf b}' the 

 curved point of the cephalotheca, the skin of the pupa splits across the 

 suture behind the cephalotheca, and along the sides of the wings, and 

 the imago emerges. The pupa state in July and August lasts six days, 

 or just twice as long as each of the preceding larval stages (except the 

 sixth, which is, as before shown, onl}^ half as long as the others). 

 Thus the duration of the larval life is nineteen and a half days, and that 

 of the pupa six days. How long the imago lives is not known, nor so 

 far as I have been able to learn has any one ever known the imago to 

 feed, and it seems probable that not only does the larva in its first five 

 stages la}' up a store of food sufficient for the two succeeding larval 

 stages in which it eats nothing, and for the pupa, but also for the 

 imago. 



I have given as fully as the time at my disposal will permit, the life 

 historj- of Lithocolletis guttijinitella. But the cj^cle of changes is not 

 always the same. I have alluded before to the observations of Mr, 

 Edwards upon the larvai of some butterflies, showing that while some 

 proceed regularly with their metamorphoses, others of the same brood, 

 from some unknown cause, will even in early summer cease to feed and 

 to grow, but will hibernate, and then pass through the remainder of 

 their changes the next summer; and I have stated that a very similar 

 fact occurs in the larvse of Lithocolletis. Early in August, some larvae, 

 after having reached this seventh stage, proceed no further with their 

 changes until the next spring, whilst others pass through all of them, 

 and in all probability deposit the eggs from which come another brood 

 in the same season. These dilatory larvae, do not spin their cocoonets 

 like the others, the}- make no fold in the upper cuticle of the leaf, but 

 simply spin the floor of their cocoonets, and attach it all around its 

 edges to the upper cuticle, which they also cover with a sheet of silk. 

 This form of cocoonet is as roomy as the other, because it is made to 

 produce a more distinct mamillary bulge of the underside of the leaf; 

 and in it the larva remains, until the following April or May; and its 

 development is not hastened b}^ the warmth of the late summer or fall. 

 The number of larvae that pursue this course, increases from the first of 

 August on through the season until in the latter part of September 

 no other form of cocoonets will be found. 



