64 
Psyche 
[June-Sept. 
In the earlier account of the biology of Stilbula tenuicornis 
it was pointed out that the planidium feeds and attains its 
full growth while still upon the Camponotus larva, and that 
the first molt takes place just as the host is transforming to 
the pupal stage. The newly-formed second-instar larva 
makes its way from the larval skin of the host as soon as 
the latter is freed from the prepupa at the point of attach- 
ment of the parasites and it then takes up a feeding position, 
constant for the species, on the pleural region of the meta- 
thorax, beneath a wing pad, or beneath one of the hind legs, 
of the pupa. The exuvise of the planidium remains attached 
to that of the host larva and is found with it at the base of 
the cocoon. This is the only species known to undergo the 
first molt prior to transfer to the host pupa. Orasema 
wheeleri Wheeler, S. cyniformis, Chalcura deprivata, Eucha- 
ris scutellaris, and Kapala sp. are still first-instar larvae at 
the time of the host molt. The planidia of Kapala sp. are 
fully fed and consequently fully distended at this time, 
whereas those of C. deprivata and E. scutellaris show no in- 
crease in size or separation of the segmental bands, and 
they presumably do not feed extensively until the host pupa 
is reached. 
The increase in size of the planidium before the first molt 
is relatively enormous, and Parker (1932) mentions an in- 
crease of 1,000 times in Stilbula cyniformis. In Schizaspidia 
convergens the body length is approximately 1 millimeter 
as compared with one-tenth that length for the newly 
hatched individuals, and the increase in volume approxi- 
mates the figure given by Parker. There was some doubt 
that this larva was actually the first instar, rather than the 
early second with the exuviae still enveloping the body. Upon 
close examination, however, the mandibles of the heavily 
sclerotized first-instar head were seen to move, and when 
the larva was removed from the host and then replaced the 
mandibles were again imbedded in the skin. 
As soon as the larva, in either its first or early second 
stage, becomes attached to the host prepupa or pupa its feed- 
ing and consequent growth are exceedingly rapid. Only a 
single feeding puncture is made, and in Stilbula tenuicornis, 
Schizaspidia convergens , Kapala terminalis and Chalcura 
deprivata the contents of the host pupa are completely 
