Feb. 12,1917 
Tetrastichus bruchophagi 
279 
STAGES OF HOST SHOWING PARASITISM 
Tetrastichus bruchophagi is parasitic upon the larval stage of its host, 
B. funebris. This parasite attacks the half-grown or fully developed host 
larva, and after attaching itself punctures the host larval skin, feeding 
upon the body contents. It is normally an external parasite but in 
several instances has been found to be completely inclosed within the 
host larva. 
One hundred and eleven larvae of T. bruchophagi under observation 
showed 106 of these parasite larvae as externally parasitic and 5 as inter¬ 
nally parasitic upon their respective host larvae. All of the specimens 
counted in this test were reared to the adult stage for determination. 
This species has not been observed to be parasitic upon the pupal stage 
of its host. 
HIBERNATION 
This species hibernates within infested seeds of alfalfa in which it has 
attacked its host, and spends the winter in the larval stage. Larvae 
becoming fully developed as early as August and September frequently 
go into hibernation. In a few instances this species was observed to 
enter the pupal stage late in the fall and to pass through the winter in 
this stage. Most of the pupae and undeveloped larvae are killed by the 
first severe frost in the fall. 
APPEARANCE IN THE FIELDS 
Tetrastichus bruchophagi is probably the first of the parasites of B. 
funebris to appear in the fields in early spring. A comparative study of 
larvae of this species, together with other parasites of B. funebris , shows 
that the larvae of T. bruchophagi are among the first to transform to the 
pupal stage and emerge as adults with the approach of warm spring 
weather. The adults may be seen among the first blossoms of alfalfa 
and are active over the first developing seed pods. 
Table I shows the emergence of adults of Tetrastichus bruchophagi , 
reared from larvae which had hibernated through the winter; and Table 
II the emergence of adults of the summer generations as they appeared in 
the laboratory, from- alfalfa seed infested with B. funebris and taken 
from the fields. 
