Chase—Length of Life of the Larva of the Wax Moth . 267 
The larvae when they hatch are very small, under two milli¬ 
meters in length, colorless, and extremely active. They run about 
rapidly, using only the true legs and not allowing the rest of the 
body to touch the surface on which they move. When disturbed, 
they can run backward nearly as readily as forward. As soon as 
they are hatched, they spin a silken thread by which they drop 
from one part of the comb to another. After the first ecdysis, 
a change takes place in their appearance and movements. They 
can still run rapidly, but are in the comb eating and tunneling 
and in less danger. They are longer in proportion to their width 
than before, and are beginning to use the prolegs as well as the 
true legs in crawling. From this period on in succeeding ecdyses, 
the larvae continue to change slowly. The body grows somewhat 
gray in color and the chitin of head and tarsus becomes browner, 
though immediately after each ecdysis the body is colorless. At 
the time of the third or fourth ecdysis, fine hairs become visible 
forming a protection for the body, the motion is slower, and the 
dorsal body surface curves slightly upward, making the shape 
of the mature larva differ from that of the first instars which are 
flattened dorsoventrally. At the beginning of the last stadium, 
whether eighth or ninth, the larva becomes very dark, almost black 
in color. This condition continues for three or four days, and 
then the larva becomes normally gray, remaining so until pupa¬ 
tion. This color change at one definite period in the life has not 
yet been explained. The larva just before pupation is between 
two and three centimeters in length and nearly round in cross 
section. It wanders about until a suitable place is found, usually 
outside the comb, and there spins its cocoon, taking from one to 
three days to complete it. The cocoon of white silk with bits of 
wax and excreta fastened to it, when finished, has at one end a 
partial opening of two, three, or four Y-shaped flaps fastened to¬ 
gether with a few silk threads to make escape easy for the emerging 
imago. The opening is probably cut by the larva after spinning 
rather than spun in such form originally. 
Zoological Laboratories, 
University of Wisconsin 
