142 Annals Entomological Society of America __[Vol. VII, 
the circumference nearest the caudal end of the pupa. The 
larva evidently constructs this circular incision by rotating 
the head through about 240 degrees, cutting the epidermis 
with the mandibles as it goes. Needham (’08, p. 270) in dis- 
cussing this matter makes the following statement: ‘‘Just 
before transformation to the pupal stage the larva eats a hole 
out to the epidermis and returns to the center of the cavity; 
this hole is a passage of exit for the adult, which then has 
only to break through the transparent epidermal window to gain 
its liberty.’’ One would infer from this statement that the 
window is opened at the time of the emergence of the adult 
by the rupture of the epidermis, but this is not the case. Also 
no mention is made of the fact that the epidermis is cut in any 
way. The evidence is conclusive that the operation of opening 
the window is not a mere rupture of the epidermal tissue 
since: (1) Very careful examination shows that a circular 
incision is actually made and that the translucent window is 
merely pushed open at emergence, (2) it is an easy matter to 
open one of these windows on a gall from which the adult has 
not emerged by either carefully inserting the point of a needle 
between the edges of the incision, or by splitting the gall and 
applying very slight pressure against the inside of the window, 
which in either case opens as a hinged shutter with the attach- 
ment constant in position, and (8) an examination of a large 
number of petioles from which the adults had emerged showed 
that in every case the window opened as a hinged shutter, 
the attachment of which always had the above described, 
definite relation to the body of the gall and to the pupa. If 
the opening of the window was a matter of rupturing the 
epidermis there would be no possibility of this constancy in 
the form of the opened window. It should be mentioned in 
this connection that the incision is not an absolutely con- 
tinuous one, since a few minute portions of the tissue are left 
uncut and serve to hold the window closed up to the time of 
emergence. It is therefore possible, under average conditions, 
to determine from the exterior whether or not the adult has 
emerged. If the window is not loose around the edges the 
insect is still within the gall, but if the window is loose and 
gapes slightly it is very strong evidence that the adult has 
emerged. An exception to this rule may occur in a petiole 
