MUNSON: SPERMATOGENESIS OF PAPILIO. 
47 
margin of the wing. Close to the posterior margin, which is black, 
there is a line of yellow dots which underneath form a continuous 
band on the fore wing. This latter character differentiates it from its 
close relative, Papilio turnus. 
Ecological Observations. 
Papilio rutulus makes its appearance each year between the middle 
of May and the first of June, and remains with us throughout June, 
July, and August. I have never seen it after the first of September. 
The females seem to come earlier than the males. They are easily 
caught while visiting their favorite flowers, as pansies, milkweed, or 
while resting on branches or leaves of trees, especially in the early 
part of the day. They are on the wing most of the time during the 
middle of the day, flying with stately ease and grace always in a zigzag 
course. A very large percent of those caught during the early part of 
the season, say the first of June, are females, while those caught the 
latter part of July were with only few exceptions males. 
I have always gathered a considerable number of larvae in the fall 
and kept the chrysalids during the winter in my laboratory where the 
temperature is somewhat variable yet always higher than out of doors. 
The confinement in a warm room does not seem to hasten the develop¬ 
ment into the mature butterfly, for they come out no sooner than those 
outside. 
% 
The larva (pi. 12, fig. 2), I believe, feeds primarily on the leaves of 
the willow. It is green and not easily found in Nature while feeding. 
Between the first of September and the first of October, they leave 
their feeding places, and wander about apparently in search of suitable 
places for pupation. They are most frequently seen after the first 
autumn frost when the leaves begin to fall. They are then seen on 
sidewalks, on fences, and in wood piles. Soon after leaving their 
feeding grounds, and a week or two before pupating, their color changes 
from a bright green to a deep brown, apparently in imitation of the 
leaves changing to a similar color from the effects of heavy frosts. 
The caterpillar is often found on early frosty mornings on some ex¬ 
posed plank or fence, clinging motionless with its prolegs while raising 
the anterior part of its body in an almost vertical position with its 
front legs folded under its head, an attitude which under the circum¬ 
stances, seems pathetic enough. 
