1322 Roger C. SMITH 
Length of pupal life 
The shortest periods of time from spinning to pupation in the dif- 
ferent species was from three days to twelve days. Records of from ten 
to twenty days were more frequent than earlier ones. In overwintering 
generations, which remain in the cocoon as prepupae, this molt does not 
occur for a period of from four to eight months. The pupae emerged 
from the cocoon in a minimum of five days after pupation. This gives 
a minimum of eight days in these rearings for the length of pupal life. 
Records of from twelve to twenty-five days, however, were more frequent. 
Development was most rapid in midsummer. 
Emergence of the pupa 
When the pupa has matured, it leaves the cocoon through a cireular 
opening at one end. This opening is generally directly opposite the 
black disk, though in rare cases this disk, which is the molt, may be 
located on the side. The pupa, by exerting sufficient upward pressure, 
causes the end to tear in the form of a circular lid, which was observed 
in all cases to be hinged by at least a few threads. 
A question has arisen as to the exact manner in which this lid is 
formed. Some writers state that it is spun into the cocoon, others that 
it is cut free from the cocoon by the large pupal mandibles, and still 
others that it is torn by upward pressure. The writer has not observed 
anything at spinning that might be interpreted as the formation of this 
lid in any species. If it were cut by the mandibies, it appears that the 
edges might be jagged and somewhat irregular, yet this is not the case. 
Furthermore, cocoons would occasionally be found with the jaws pro- 
truding in the act of cutting the ld, yet this has been neither seen nor 
reported. 
The writer is not definitely convinced as to the correct explanation. 
It appears most likely to be a combination of the above explanations. 
The cocoon is so constructed that, when a rent is started, it tears In a 
circle with clean edges. Near the ends, one can tear off a hd; near the 
middle, however, the ends of the tear do not meet, but a narrow strip 
lke a continuous apple peel results. Therefore the manner of spinning 
may account for the end tearing in the form of a lid. 
It has been repeatedly observed through the thinner cocoons, as of 
Chrysopa rujfilabris and C. plorabunda, that the pupa is able to shift its 
position with surprising rapidity. This can be demonstrated by exert- 
ing a little pressure on the exterior of the cocoon. The pupae have | 
been observed to turn quickly to avoid injury. By raising its head 
shghtly, a pupa can bring pressure to bear on the upper end of the 
