16 
BULLETIN 1222, U. S. DEPARTMENT OF AGRICULTURE. 
CORRELATION WITH TIME SPENT IN NURSING. 
The effect of these food requirements upon the amount of work 
necessary to be done by the nurse bees in relation to the rate of 
growth of the larvae and nature of the food is well illustrated by 
the observations of Lineburg in Part II of this bulletin. He found 
that in the time spent by nurse bees in caring for larvae there is prac- 
tically 100 per cent increase on the first day over that at the time of 
hatching from the egg. Food is never placed in the cell until soon 
after the larva hatches. On the second day this again decreases 
about an equal amount, but begins to increase again to a remarkable 
degree, particularly after the third day. From the third day on 
the living weight (fig. 2) and the 
time spent in feeding (fig. 13) show 
a remarkable correlation. The high 
point for feeding on the first day 
corresponds with the maximum ex- 
cess of unconsumed food in the cells 
at this time. It seems probable that 
the nurse bees place an excess of the 
predigested food in the cell soon 
after the egg hatches, sufficient for 
the larva for about two days, so that 
only a minimum of attention is re- 
quired until the change in the com- 
position of the food takes place, at 
which time increasingly greater de- 
mands are made by the larva for 
honey and pollen. 
Since the greatest relative increase 
in growth takes place during the 
period of uniform, highly nitrogen- 
ous food and the greatest storage 
of reserve energy-producing mate- 
rials occurs after the food has 
changed in composition it may be 
assumed from the observations cited 
that any variations in honey-flow will affect the rate of growth of 
the older larvae more than the younger larva-. 
GENERAL APPEARANCE OF LARV^ OF DIFFERENT AGES. 
The general appearance of larvae of different ages, particularly 
with reference to their size and position in the cell, provides criteria 
by which to judge the age of the brood. 
The newly hatched larva (fig. 6) has a total length of l.G milli- 
meters. It is usually bent in a curve approximating a semicircle and 
lies on its side on the bottom of the cell. At this stage it is slender 
as compared with the later stages, tapers gradually from the head, 
and is nearly transparent. It usually lies near the center of the base 
of the cell in a mass of transparent larval food which does not exceed 
in diameter one-half that of the base of the cell. A circle drawn 
around the larva in its usual flexed position would closely approxi- 
mate 1 millimeter in diameter (fig. 1). A larva may lie on either 
Fig. 6. — Larva of honeybee newly 
hatched from the egg. 
Figures 6 to 11 were all drawn 
with the aid of the camera lucida 
from material preserved in alcohol. 
A special effort was made to secure 
as far as possible specimens repre- 
sentative of the average size of 
larva? of the age designated. In 
figures 6 to 10, inclusive, the larva 1 
are represented as seen from the 
mouth of the cell, the outlines of the 
latter being represented by a hexa- 
gon and drawn accurately to scale. 
