1924] 
The Biology of Trichopoda pennipes Fab. 
57 
THE BIOLOGY OF TRICHOPODA PENNIPES FAB. 
(DIPTERA, TACHINID^), A PARASITE OF THE 
COMMON SQUASH BUG.* 
By Harlan N. Worthley. 
Massachusetts Agricultural Experiment Station, Amherst, Mass. 
PART II. 
MORPHOLOGY 
In the study of the adult anatomy, pinned dried specimens 
were used. For the definition of the mouth parts, sclerites of the 
thorax, and the genitalia, however, it was found necessary to 
relax the parts and examine them in liquid. For this purpose, 
specimens were soaked for about an hour in a cold 10 per cent 
solution of caustic potash (boiling often causes distortion of the 
parts) washed in water and treated with . weak acetic acid to 
stop the action of the caustic potash. They were then placed in 
70 per cent alcohol. 
The parts were examined under a Zeiss binocular micro- 
scope, at magnifications varying from sixteen to sixty-five 
diameters. Many structures were obscure except under the 
brightest illumination, and therefore most of the examinations 
were made in the rays from a powerful lamp. A Ford headlight 
was mounted on a ringstand and connected through a trans- 
former with the ordinary one hundred and ten volt circuit. 
This lamp proved to be quite satisfactory, since it was placed on 
the desk at a distance of two feet from the binocular, allowing 
plenty of room to work. A lamp of this kind, focussed upon the 
microscope stage by means of the set-screw in the lamp, throws 
little light into the eyes and develops little heat, while the object 
under observation is brought into strong relief. 
*The first portion of this article appeared in Psyche, vol. 31, pp. 7-16, 
February, 1924. 
