482 NOTES ON VARIOUS INSECTS. 



minute ichneumon) — is best explained by your correspondent's 

 supposition ; the rest is a mystery ! 



Note E. — This helps to explain why one year some Hymeno- 

 pteraWiW abound, and the next they are not to be met with; but 

 these periodical appearances are not regular, the intervals vary- 

 ing much. We know nothing, or next to nothing, yet, as to the 

 laws which regulate the distribution and appearance of insects. 



Note F, — This larva is probably the pupa of a Chrysis, or 

 Hedychrum, most likely the former, and shows that they also 

 spin a cocoon. 



Note G. — This is an important communication. It also 

 helps me to allude to Waterhouse's hypothesis — (as was stated 

 in the discussion at the last meeting^^ of the Entomolooical 

 Society, where, however, I did not happen to be, but a friend 

 related it to me subsequently) — as to the necessity that regu- 

 lates the hexagonal structure of the cells of the hive bee. The 

 female hornet instinctively adopts this shape for the cells, and, 

 as well as the parent wasp, working alone, (for they must both 

 build cells for their young before they commence laying their 

 eggs,) consequently there is no antagonist force moulding them 

 by necessity into this form ; the argument deduced from occa- 

 sional irregularity of figure is of no value, and refers chiefly to 

 the external cells, where, for the smoothness of the external 

 surface, combined with a saving of material, the exact hexagonal 

 form is not adopted. The hexagonal structure in the hornet's 

 and wasp's nest, as well as of the bee, is of ancient notoriety 

 and admiration. It is not on this account that your corre- 

 spondent's note is useful, nor merely from its showing that the 

 hornet will select other places than hollow trees for building in, 

 which was before known, but it exhibits the instinct of the 

 creature in deserting, even after the expenditure of much time 

 and labour, a habitation that she foresaw would fall about her 

 ears. What a lesson ! If by chance the desertion was not 

 forcible, viz. her accidental destruction, she could not, I think, 



* At the last (the October) Meeting of the Entomological Society, Mr. 

 Waterhouse said, that what he had stated at the former meeting, relative to the 

 manner in which the comb was constructed, ditilsred in no wise from what he 

 had previously published on the subject, which I presumed had been the 

 case from its being brought into discussion. I state this merely to show, that 

 altliough the last meeting is mentioned in the note, the observation refers to the 

 last but one. 



Oct. 25, 1838. W. E. S. 



