376 
Psyche 
[September 
observed twice, and portions of the process were observed several 
other times. All emergences (except that of a female attended by 
a male — • see above) were nearly identical. First the pupal skin cover- 
ing the dorsal surface of the thorax and head split, and the adult 
began to emerge through this hole. The insect was nearly motion- 
less during this process, and its forward movement through the pupal 
skin probably resulted from peristaltic contractions of its abdomen. 
About eight minutes after the head and thorax first began to emerge, 
the legs, which by now were nearly free, began to twitch. The fly 
gradually pulled them forward and out of the pupal skin, then 
extended them horizontally so they were perpendicular to its longi- 
tudinal axis. The wings came free about four minutes later; at 
first they were soft and slightly bent, but they soon straightened and 
began to harden. After about 15 minutes, the entire animal was 
free from the pupal cuticle except for the terminal segments of its 
abdomen which were just inside the skin and supported the animal 
as it hung facing downward. While the fly hung in this position, 
the diameter of its abdomen decreased, and its new cuticle hardened. 
After about two hours the fly seized the pupal skin with its legs 
and swung its abdomen free of the skin. Undisturbed individuals 
hung motionless in this position for an additional hour or so before 
flying away. 
The mechanisim by which the flies supported themselves with the 
tips of their abdomens while they hardened was clarified when one 
fly fell completely free from its pupal skin unusually early. The 
last two segments of its abdomen were flexed dorsally so they formed 
a right angle with the rest of the abdomen. Apparently this crook 
at the tip of the abdomen is wedged tightly enough in the anterior 
end of the pupal skin that the weight of the fly’s entire body is 
supported. 
Discussion 
The observations of pupation indicate that the larval cuticle is 
not shed prior to pupation, that the last two and one half segments 
of the larva are discarded, and that the larval head capsule is en- 
gulfed by the pupa during pupation — all phenomena apparently 
undescribed in other Diptera (Imms 1964). It appears that the 
larval head capsule may migrate the length of the pupa after being 
engulfed. Head capsules appeared to be emerging from the ventral 
surfaces of abdominal segment #8 of some preserved pupae, and 
were on this surface, completely free of the pupa in others which 
