16 
Psyche 
[February 
and new adult squash bugs in the fall. Thus it would seem that the 
activities of Trichopoda pennipes furnish an exceedingly im- 
portant natural check upon the increase of Anasa tristis. 
Summary 
Trichopoda pennipes is a parasitic fly belonging to the 
family Tachinidse. The species enjoys a wide distribution in 
the lowlands of North and South America and the adjacent 
islands, and has been recorded as attacking several species of 
insects belonging to the hemipterous families Coreidse and 
Pentatomidse. Among these hosts is the common squash bug, 
which in Massachusetts is the principal host, and possibly the 
only one attacked by the fly. 
The investigations recorded in this paper indicate that 
in Massachusetts this parasite passes through two full generations 
annually. Adults of the first generation deposit their eggs on 
egg-laying adult squash bugs, during July. Those of the second 
generation attack the older nymphs and new adult bugs in 
August and September. Collections of squash bugs have in- 
dicated a parasitism of eighty per cent. Squash bugs which are 
parasitized in the fall apparently do not live to sexual maturity, 
and thus an important natural check is placed upon the increase 
of the squash bug. 
