Thk Pistol-Case-Bkarer. 1 1 



the pistol-case-bearer does not construct an entirely new and 

 larger suit to accommodate its increasing size. It simply pieces 

 on additions to its suit from time to time. In the enlarged cases 

 represented at b, b, plate 2, the white portion at the head end is 

 a very recent addition to the case ; the right-hand figure also 

 shows a slight addition around the anal orifice. We have speci- 

 mens of cases which show fresh, white additions all along the 

 lower edge of the case as well as at both ends. These additions 

 seem to be made mostly of silk in which is mixed considerable of 

 the pubescence and debris of the leaves, and the whole is glued 

 together to form a tough leathery substance. Although white 

 when first made, the additions soon become stained a very dark 

 brown, perhaps from the excremental or other juices of the cater- 

 pillar. After about May ist, the caterpillars seem to confine 

 nearly all of their extensions to the head end of their suits, thus 

 considerably lengthening the barrel of the ''pistol." When 

 complete then, their cases are simply their first winter suit that 

 has been made larger around and longer by additions or patches 

 put on to one side and both ends. Externally the cases or suits 

 present a rough, fuzzy, somewhat untidy appearance, but cut one 

 of them open and take a peep inside. The whole suit is found to 

 be lined with a thin, smooth, whitish, delicate layer of silk which 

 gives the interior a neat, cozy appearance. 



The curved end which forms the handle of the *' pistol " con- 

 sists of two flattened oyster-shell-like projections of the suit, which 

 are not joined together along their lower edges, and thus form a 

 slit-like opening that is the back-door to the case. The elasticity 

 of the material and the peculiar curve of this portion of the suit 

 tend always to keep this opening closed. It would require con- 

 siderable force for an outside enemy to open this orifice, though 

 from the inside the slightest pressure enables the caterpillar to 

 protrude its anal segment whenever its excrement is to be voided. 

 This arrangement enables the little caterpillar to keep his snug 

 home neat and clean inside. This back-door also serves another 

 important purpose in the life of the insect, as we shall see later. 



Moulting of the caterpillar. — On April 26th, we were surprised 

 to find that most of the caterpillars at work in our cages had 

 securely fastened their cases to the bark of the twigs as shown at 



