Notes in 1887 upon lepidopterous larve, dc. 587 
of the Hymenopteron, and was not a mere scratch from 
one of its claws. The blood of the lepidopterous larva 
forms a black clot, so that wounds are nearly always 
black until after the next change of skin. On these 
accounts I think it is clear that the black marks exposed 
by the larva are calculated to suggest to the approaching 
enemy that the individual in question is already occu- 
pied. This interpretation will receive further support 
in the next section, in an instance of the use of the 
same colour by the ichneumon itself for an entirely 
analogous purpose. 
The black marks of S. fagi are also very interesting 
from a morphological point of view. In common with 
the terrifying marks of A. tau, previously described, 
they have the structure of eversible glands, which are 
so common in larve, and of which I have described 
many in earlier papers. It is possible that this may 
have been their original significance, but whether this 
be so or not, I think it is almost certain that they have 
played the part of terrifymg marks in some different 
form of alarming attitude formerly adopted by the 
larva. Their exact similarity to the marks of A. taw 
is in favour of this view, for there is no doubt about the 
meaning of the character in the latter species. The 
only difference between the two larve is the presence of 
the mark on the Ist and 2nd abdominal segments in 
Stauropus, andonthe 1st abdominal onlyin Aglia. Other 
reasons for this opinion are to be found in the facts that 
the marks arestill very large for their purpose (inasmuch 
as the scars are rarely of such a size), and that the 
opening and closing apparatus still remains in perfect 
working order. The latter has a definite meaning for a 
terrifying mark, but it is difficult to see how it can have 
been developed in connexion with the imitation of a 
scar, which is, of course, persistent. There is no 
difficulty, however, in understanding why it should have 
been retained in connexion with such unnaturally large 
scars, for continued irritation of the larva shows that 
this is one of the last resources adopted when the 
enemy has already discovered it. The continued display 
of such large marks would certainly interfere with the 
protective resemblance in the passive resting-condition. 
The same objection would hardly apply to a mark 
which resembled a scar of the commonest size, viz., such 
TRANS. ENT. SOC. LOND. 1888. PaRTIv. (DEC.) 2R 
