152 
Journal of Agricultural Research 
Vol. VII, No. 4 
DESCRIPTION 
The newly formed pupa is white with salmon-colored eyes and Ocelli; 
before transforming to the adult stage it becomes almost black in color. 
It averages 1.8 mm. in length. The head and tip of abdomen are bent 
slightly forward. The wing pads, legs, and antennae, folded close to the 
body, are visible through the thin pupal skin (PI. 4, fig. E). 
length of pupal stage 
The length of the pupal stage varies greatly even in midsummer. 
This stage requires about 10 days under favorable field conditions in 
midsummer. Under laboratory conditions approximating out-of-door 
temperatures the pupal stage varied from 10 to 52 days, the long pupal 
stages being recorded in the months of March and April. 
Larvae, after hibernating through the winter, pupated in the spring 
and showed the following average period in the pupal stage: In March, 
23 pupae averaged 14 days; in April, 39 averaged 23 days; in May, 8 
averaged 21 days; and in June, 4 averaged 18 days. 
ADULT 
The adult (PL 4, fig. A), upon emerging from the thin pupal skin, 
finds itself completely inclosed within the alfalfa seed and within the seed 
pod. It at once gnaws its way out, escaping by the small irregular open¬ 
ing which it makes. 
CHOICE OF HOST PLANTS 
H. medicagmis was not found to be present as a parasite of S. funebris 
when the latter infested the seed of red clover. This was true even where 
the red clover was taken near alfalfa fields and H . medicaginis was known 
to be present. 
RELATIVE PROPORTION OF SEXES 
Some localities from which this species was reared showed apparently 
no males, while in other localities a few males were found. The pro¬ 
portion of males is, however, very small to that of the females. Reared 
adults were counted to get the proportion of sexes. It was found that 
270 of these were females and 9 were males. This showed a ratio of 1 
male to 30 females. 
SEASONAL HISTORY 
In western Arizona and southern California H, medicaginis appears in 
the adult stage as early as the month of March. It is in its greatest 
abundance during July and August on irrigated alfalfa fields. On drier 
lands, where the seeds are subjected to desert conditions, many of the 
larvae are driven to an early dormant period and the adults become less 
abundant in the hot months. Under extremely variable conditions there 
are from one to at least four generations in a single season. One larva 
