68 
Psyche 
[April 
Two characters were found by which the sex of living flies 
can be determined without undue handling. These are the 
ferrugineous spot in the wing of the male as against the evenly 
dusky wing of the female, and the black tip of the female ab- 
domen as against the dark orange of that of the male.i A minor 
difference was in the size of the pulvilli, these being shorter than 
the last tarsal segment in the females, and inconspicuous. In 
the males the pulvilli were longer than the last tarsal segment, 
and quite broad and conspicuous. This is a character, however, 
that is not readily noticed unless a male and a female are examined 
at the same time, and it is therefore of little practical use, in a 
taxonomic sense. 
Egg. pi. Ill, fig. 16. 
The eggs of Trichopoda pennipes vary in color from clear 
shining white to dirty gray, the coloration seeming not to depend 
on the age of the egg. The individual egg is ovate in outline, 
being slightly larger at one end. It is strongly convex, and is 
flattened on the side next the body surface of the host. This 
flattened surface is covered by a colorless cement, by which the 
egg is affixed to the body of the host. The egg measures .56 mm. 
in length by .37 mm. in breadth, and its greatest height is .25 
mm. The surface of the chorion appears smooth except under 
high magnification, when it is seen to be faintly reticulate in 
tiny hexagons. The chorion is comparatively thick and ‘deather- 
y”, and remains rigid after hatching. The micropyle appears 
to be borne on a small papilla at the smaller end of the egg. 
Eggs which have hatched show a circular hole on the flattened 
side near the broader end. Since it is this flattened side which is 
pressed against the host, it is impossible to tell if an egg has 
hatched without first removing it from the body surface of the 
host. 
Larva. PL III, figs. 17 and 18. 
The larva has not been examined in all instars. When 
fullgrown, it is a dead-white maggot, with black hook-like 
^Drake (1920) published recognizable photographs of both sexes, but his 
designations are erroneous. Osten Sacken, in a foot-note to the work of Say 
(1829), also has confused the sexes. 
