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I 873.] - Zoölogy. i : 559 
The first appearance of the parasite is represented in Fig. 1. 
A warty excrescence appears on the back of the caterpillar, which 
slowly emerges until it is seen to be a larva enclosed in a delicate 
transparent membrane, as represented in Fig. 2. This it soon 
succeeds in bursting, and rising to its full length, balances itself a 
moment as in Fig. 3, then bending double it ejects from its 
mouth a glairy liquid, which instantly changes to silk and fastens 
E ed ee eed 
Fics. 1-13.—Ichneumon (Microgaster) spinning its Cocoon. 
the posterior end to the skin of the caterpillar, as shown in Fig. 
4, side view. It now begins to spin its cocoon by attaching ¿ a 
silken thread to the silky mass by which it had previously fas- 
tened itself to the caterpillar, and forming a series of loops of 
uniform size, first from right to left and then back again from left 
to right, as represented in the front view, Fig. 5, and better in the 
enlarged view Fig. 5 a, the arrow-heads 
showing the direction in which the head of 
the larva moved while forming the loops. 
The ends of the series, numbered 1, 2, 3,4, 
are fastened to the edges of the ventral 
side of the body, which thus serves as a 
measure of the width of the cocoon and | 
also acts as a support for the frail fabric in $ 
the first stages of spinning. After the 2 
larva has fastened the fabric as far x on == 
its ventral surface as it can, conveniently, Fic. 5 a. 
it then begins to spin free, as shown in the side view, Fig. 6, 
where it is represented as just completing the first half of its 
cocoon which resembles in form a slipper. is accomplished, ; 
the larva ceases to spin for the time being, bends its head, as in 
Fig. 7, towards its ventral surface and pushes the half cocoon free 
from its body. The form of the silken fabric enables it to stand 
unsupported, while the larva, sliding its head down to the base, 
holds on firmly until it swings it posterior end into the toe of the oe 
slipper. os 
Fig. 8 shows it in the act of changing end for end, and in Fig. 
ae larva is seen erect, beginning at the base to complete the: 
