Oct. S3. 19x6 
Life History of Habrocytus Medicaginis 
151 
become dried from the hot desert winds before the parasitic larva has 
completed its development, a prolonged resting period may follow. 
This period may vary from a few weeks to a year. With combined 
moisture and a warm temperature the insect resumes its development 
toward the formation of the pupal stage. 
description 
The larva is grublike and almost white in color and averages 1.6 mm. 
in length when fully developed. It is cylindrical in shape and rounded 
anteriorly and posteriorly. Head medium-sized and slightly bilobed. 
Mandibles almost invisible. It has a small inconspicuous tubercle on 
each eye lobe. There are 13 body segments of approximately equal 
length, except the first two, which are slightly longer; segmentation 
medium. Body skin usually slightly wrinkled, but sometimes smooth j 
glossy, and free from pubescence. Anal segment divided into a dorsal 
and a ventral lobe. Three fine setae on dorsal lobe (PI. 4, fig. C). 
LENGTH OF LARVAL STAGE 
The length of the larval stage depends greatly, as has been previously 
stated, upon the resting period following the development of the larva. 
A small newly hatched larva began feeding Upon its host under observa¬ 
tion on April 23. It showed noticeable growth from day to day, and by 
April 27 it had completely killed its host. On May 5 the larva trans¬ 
formed to the pupal stage. Another newly hatched larva dissected 
from a green alfalfa seed began feeding upon its host on September 5 
and by September 7 the host was killed. The larva was apparently fully 
developed by September 11. Others removed from alfalfa seeds in 
August did not pupate until the following April. The minimum length 
of the larval stage as observed by the writer is normally about 12 days. 
The maximum length is a year or more. 
PREPUPAL FORM 
Just before entering the pupal stage the larva of H. medicaginis dis¬ 
charges an excessive amount of excrement. This is followed by a 
lengthening of the anterior body segments and the shaping of the pupa 
within the larval skin. The prepupal form requires two or three days 
unless retarded by unfavorable conditions. 
THE PUPA 
FORMATION 
Pupation takes place after the pupal form has developed within the 
larval skin. The larval skin breaks along the dorso-anterior margin and 
is slowly worked back until the newly formed pupa is exposed. 
