56 [August, 



the moulting of the larva. The batch, however, is considerably longer 

 in going through the last metamorphosis than it was in changing from 

 larvae to pupae. As usual, the main body come more closely together, 

 while there are loose stragglers both before and after. Nor do the 

 pupae become beetles in the same order in which they became pupae. 



The newly excluded beetle is at first pale yellow, with the excep- 

 tion of the parts above mentioned, but soon acquires its natural 

 colours. The elytra are so soft at first, that impressions may be made 

 on them which they will retain ever afterwards, as, for example, by 

 lying on a hard smooth surface, such as that of delf. 



Male and female are not to be distinguished with any certainty 

 at first, at least by external marks alone, and it is only by the gradual 

 development of gastrophysm in the $ that the sexes can be discrimi- 

 nated. By separating the beetles, however, in the order of their 

 exclusion, I have found that in a batch the females are, on the whole, 

 the first to be excluded. In one lot, for example, of 31 beetles, I placed 

 the first 12 in the order of their exclusion in 12 boxes, correspondingly 

 numbered ; and of the remainder (disclosed the following day) six of 

 the largest and best developed were similarly isolated. Of the first 

 12 all turned out females but the 10th and 11th ; whilst among the 

 latter six there was only one $ . 



These observations were made with the further object of watching 

 the development and progress of gastrophysm in each beetle. I must 

 recall that there are four abdominal spiracles on each side, situated on 

 the first four abdominal segments of the imago ; and as the abdomen 

 enlarges and its dorsal segments become convex, not only the pygidium 

 and the margins of the abdomen are uncovered, but spiracle after 

 spiracle comes into view, and is left behind by the retreating margins 

 of the elytra, until the fourth (reckoning from behind) is fully 

 exposed. Then, and not before, the first eggs will be laid. The 

 development of gastrophysm occupies from 8 or 9 to 11 or 12 days, 

 according to the season. 



With the laying of the first eggs the cycle is complete, from egg 

 to egg again ; and the whole period so occupied I found to be at the 

 shortest 39 days — ordinarily about 6 weeks — and in colder weather 

 extending over a considerably longer time. 



The union of the sexes in those beetles which are to pass the 

 winter, would seem to be deferred till the following spring. This is 

 rather a prolonged business, when it does take place, and is frequently 

 repeated when opportunity serves, but once sufficiently effected, no 

 further re-union is necessary to the continued fertility of the ? . On 

 the other hand, the same <$ seems to be capable of fertilizing many 

 females in succession. 



