264 Wisconsin Academy of Sciences , Arts, and Letters. 
an hour a day, and often longer, by opening tbe door, was cooled 
to a considerably lower temperature. The length of the lives of 
the moths was at once greatly shortened, and they came more 
nearly to what Paddock considered normal growth and develop¬ 
ment. In this compartment the air was kept moist with stand¬ 
ing water, and the heat was regulated by a thermostat. Artificial 
conditions of darkness were in part supplied by paper coverings 
about the closed dishes in which the larvae were kept. 
Food experiments were also made. At first in the work in the 
laboratory, before temperature regulation was resorted to, bits 
of dry comb were used. The larvae were, however, usually con¬ 
cealed by boring into it out of sight, and digging them out was 
often fatal. Pieces of wax pressed hard and thin were used in¬ 
stead, but seemed to offer too great resistance to larval attacks. 
Finally, for the second and successful attempt to raise the lar¬ 
vae in the constant temperature compartment, the wax of the 
comb was chopped up, mixed with bee bread, soft dead moths, 
and honey, and kneaded into a small loaf, which was allowed to 
dry out a little and from which thin slices were cut to supply the 
larvae with food. This proved the most successful method. When 
about half grown, they were put on a diet of brood comb which 
they then had no difficulty in eating. It was noticeable that the 
newly hatched larvae, when allowed to remain together, first se¬ 
lected for food the dead bodies of the moths, later feeding on the 
comb. 
Many schemes for housing • the larvae were tried and found 
ineffective. The most satisfactory quarters in which one to six 
of them could live together proved to be thick glass slides with 
a deep hollow center which could be closed with cover slips held 
in place by a thin film of vaseline. The larvae kept in this way 
were easily accessible and could be placed for observation under 
the binocular microscope. 
The problem of marking larvae without killing them was the 
most difficult of all. While, after careful watching, it seems cer¬ 
tain that the larvae do not ordinarily eat their exuvia, which 
were found at all stages of development after ecdyses, yet these 
could not be relied on to show each molt. It was necessary to 
mark the larvae with a substance which would dry quickly and 
not easily rub off, with a brush which would not injure them. The 
most successful brush was a bird’s feather cut to a fine point, 
though single hairs were first tried. India ink was easily rubbed 
