STATES OF INSECTS. 299 



merit is produced indifferently both by males and females 

 I cannot positively assert; but a circumstance related 

 by Jurine affords some ground for a suspicion that it 

 is peculiar to the latter. A specimen of a female of 

 Lasiocampa Riibi, when killed emitted some of this 

 fluid, which dropped upon the floor : this appeared to 

 attract the males to the apartment in which it happened, 

 and to the very spot — from whence it maybe conjectured, 

 that the scent of the fluid brought them there, and that 

 the use of it is to bring the sexes together soon after ex- 

 clusion from the pupa a . 



The colour, sculpture, and other peculiarities which 

 distinguish insects in this state I shall consider at large 

 in another letter, when I treat of their external parts and 

 organs. Under the present head I shall confine myself 

 to pointing out the characters by which the sexes of many 

 species are distinguished from each other; as likewise 

 the duration of their life in their perfect state ; together 

 with the circumstances on which this duration depends. 



I. Sexual Distinctions. The first general rule that 

 may be laid down under this section is, — That among 

 insects, contrary to what mostly occurs in vertebrate 

 animals, the size of the female is almost constantly larger 

 than that of the male. Even in "the larva and pupa states, 

 a practised eye can judge, from their greater size, which 

 individuals will become females. There are, however, 

 some exceptions to this rule. Thus amongst the Coleo- 

 ptera } the male DynastidcE, remarkable for their horns, 



a Jurine Hymenopt.9, Note 1. 



