INTERNAL ANATOMY OF INSECTS. = 159 
or aura seminalis, which, though small in quantity, it may 
retain the power of emitting for a long period. | 
Certain female moths, of the species of that family 
which, from the remarkable cases or sacs the larvee in- 
habit, the Germans call sack—trdger, before noticed ?, 
have been supposed to have the faculty of producing fer- 
tile egos without any sexual intercourse; and various 
observers, after taking great pains, appeared to have sa- 
tisfactorily proved the fact ; so that some doubted whether 
these insects produced any males at all>. The enigma 
was at length explained by the accurate Von Scheven. 
At first his experiments were attended with the same re- 
sult as those of his predecessors ; but upon making them 
more carefully, and separating what he conceived to be 
the female from the male pupz, he ascertained not only 
the existence of a female in the species he examined 
(Psyche vestita), but that when thus secluded she laid 
barren egos; evidently proving that in the contrary in- 
stances above alluded to, an unperceived sexual inter- 
course must have taken place®. Though he thus ascer- 
tained that these insects do not in this respect deviate 
from the general rule, he remarked or confirmed several 
facts in their economy sufficiently anomalous and strik- 
ing ;—as that the female is not only without wings, but 
with scarcely any feature of a moth, much more closely 
resembling a caterpillar; and that in ordinary circum- 
stances she never attempts to leave the pupa-case in 
which she has been disclosed, but that being there im- 
pregnated by the male, she there also, apparently after the 
2 Vot, [spy 464. » Compare Reaum. iii. 153. 
Pallas Act. Nat. Cur. 1767. iti. 430. Wien. Verzeich. 292, 
¢ Naturfor St*. xx. 59—. 
