146 
Psyche 
[June 
four segments, almost hairless. The head is small and pale 
with the mouth parts rudimentary and the antennae very short, 
modified. The legs are soft and short with the claws absent and 
replaced by a small prominence. The processes of the body are 
much smaller and less distinct, with only a few white hairs, 
until the last three or four segments where they become rather 
thickly hairy, but with the hairs shorter than in the larva. The 
terminal processes are likewise shorter but with the spines long 
(Plate III. Fig. 2a). This skin is cast about the middle of May 
and the larva then reappears from the shell in its ordinary form 
continuing its life as before, until it is full fed in the second or 
probably in most cases the third summer. When full fed it 
changes into a second inactive winter-form which more nearly 
approaches the pupa and which like the other, may be aroused 
early or late in the year. Though this is very similar to the 
previous one, it differs from it especially in the much more 
stumpy form of the antennae and of the processes of the last 
three or four segments/ ’ 
Another author, Riischkamp, (Biol. Centralbl., 1920, page 
376-389) corroborates Grawshay’s above quoted statements 
about the life history of Drilus flavescens and gives the interesting 
information that he has been able to shorten or prolong the 
different stages by changing the degree of humidity and food. 
Such change of a larva from an active to an inactive stage could 
be brought about after only thirteen days. The larva seems to 
have the ability of adapting itself to the prevailing circumstances 
by changing over from the active to the inactive stage, whenever 
necessary or “necessitate coacta ” an extraordinary thing showing 
how plastic in their habits certain members of the large and 
undoubtedly primitive group of malacoderms are. 
The pupa of the male Drilid is a normal beetle pupa. The 
female pupa resembles very closely the last inactive form of 
lava. Thus a tendency to reduce and simplify the originally 
normal pupal stage is clearly distinguishable. 
The females of the few Drilids, the life history of which is 
known are even more larviform in their general appearance 
than are the Lampyrid females. A distinct resting period is 
undergone and the female is in all essential characters an imago, 
