DEVELOPMENT OF A HYMENOPTEROUS PARASITE 519 
fresh banana peel lives about eighteen days. The extremes were 
eight and twenty-six days in a large number of cases noted. 
The egg. The egg (fig. 2) is elongate, constricted at the an- 
terior end somewhat widened below the middle and drawn out 
into a short, blunt petiole posteriorly. It is white in color and 
measures about 0.48 mm. in length by 0.14 mm. in greatest 
diameter. 
Hypermetamorphosis in the Hymenoptera. Before considering 
the larval stages of muscidarum, it seems expedient to review 
briefly the known examples of .hypermetamorphosis in other 
hymenopterous insects. The various types of larvae are dis- 
cussed below and their distribution throughout the superfamilies 
is shown in table 1. It is impossible at this time to ascertain 
the extent of larval modifications within the different groups or 
to appreciate the phylogenetic value of the various larval types. 
Yet enough has been accomplished to suggest some very impor- 
tant characters for the more exact definition of families and genera 
as well as species. However doubtful such researches may be 
from the standpoint of phylogeny, their value in the study of 
parasitism and in taxonomy can hardly be questioned. 
Ratzeburg (’44) figures the larval forms of the Ichneumonid, 
Anomalon circumflexum Linné, which passes through a remark- 
able series of stages. The first stage larva is found in the small- 
est lepidopterous larvae. Its caudal segment is greatly pro- 
duced, equaling about half the body in length and is sharply 
pointed. The alimentary canal can be seen by means of the 
microscope, running out into the caudal appendage. The head 
is chitinized and is armed with a pair of mandibles. There is 
no trace of a tracheal system. In the second stage larva, the 
tracheal system begins to develop along the dorsum and the 
caudal appendage is reduced from one-half to one-fourth of the 
body length. Single-jointed antennae appear on the head. The 
third stage larva has a fully developed tracheal system. A pair 
of antennae, a pair of large curved mandibles, a pair of maxillae 
and a pair of smaller labial palpi are visible. This larva is 
inclosed in a peculiar sac. The fourth stage larva is entirely 
without a caudal appendage. The chitinous character of the 
