ADMISSION OF AIR IN COCOON OF BEES 623 



resembles in form a slipper. This accomplished, the larva ceases to spin for 

 the time being, bends its head, as in 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 its posterior end into the toe of the slipper. 



Figure 572, 8. shows it in the act of changing end for end, and in 9 the larva 

 is seen erect, beginning at the base to complete the other half of its cocoon ; 

 10 shows the larva contracting its body as it spins upward for about half the 

 length of the cocoon, when it again changes end for end, as shown in 11, where 

 it is beginning at the upper part to unite the two sides, finally enclosing itself 

 as represented in 12. 



It may now be seen, under the microscope, through the meshes of its cocoon 

 actively engaged in lining the interior with layers of very fine silk ejected from 

 its mouth in great abundance. One half of the cocoon is first lined by a forward 

 and back movement of its head, and then reversing its position, it lines the 

 other half in a similar manner. 



In one case the larva was disengaged from the skin of the caterpillar, after 

 beginning its cocoon. It, however, began again, and spun a portion while lying 

 "on the table. This was removed, when it began a third time, and completed its 

 cocoon. 



In about 10 days the insect made its appearance through a hole in the upper 

 end, as represented in 13. The top was eaten off in a perfect circle and hung by 

 a few threads, so as to resemble a lid as it was thrown back. 



One caterpillar observed had between 300 and 400 cocoons on its back and 

 sides, and another was dissected after more than 30 larvae had escaped, and 

 130 were discovered in the soft integuments of the back. 



The figures from i to 13 are magnified five diameters, but in order to observe 

 the spinning of the cocoon a power of 50 is required. (Amer. Naturalist, xii, 

 pp. 559, 560.) 



Certain differences observed by W. A. Buckhout in a Microgaster parasitic on 

 the different species of Macrosila, are referred to in the same volume, p. 752. 



While those chalcidid larvae 



which feed internally on their ' * 



host, as a rule, transform into 

 naked, more or less coarctate 

 pupae, Howard states that the 

 larvae of Copidosoma, Bothrio- 

 thorax, Homalotylus, and per- 

 haps others, which are much 



j j .... ., . , FIG. 573. Body of larva of Lithorollctis, swollen 



crowded within their host, cause and fllled with C0 coons O f Copidosoma, enlarged. 



a marked inflation of the body of 



the latter (Figs. 573, 574). The nature of this cocoon-like cell, and how it is 

 produced, is unknown. "Its structure shows it not to be silk, nor yet the 

 last larval skin of the parasite, and whether it is an adventitious tissue of the 

 host-larva or a secretion of the parasite, or is explicable upon other grounds, I 

 cannot say." 



The silken cocoon of an aphidiid ichneumon has been found by Miss Murt- 

 feldt, and also by Dr. Riley, under a rose aphid in which it had lived, and 

 referred by Howard to the genus Praon (Fig. 575). 



Sanitary conditions observed by the honey-bee larva, and admission of 

 air within the cocoon. Cheshire has observed that after the larva 

 of the honey-bee has spun its cocoon or silken lining of its cell, it 



