298 STATES OF INSECTS. (Imago.) 
ment 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 Rubi, 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 may be 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?. 
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 Dynastide, remarkable for their horns, 
as you may see in Strategus Aloeus, Anteus ; Megasoma 
* Jurine Hymenopt. 9. Note 1. 
