X, B, 5 Roberg: Bacterial Infections 315 
Sometimes the abdomen is black or dark reddish ferruginous with the 
centre part generally pale, forming a light wide irregular dorsal stripe. 
Belly generally brownish yellow or some kindred shade. 
Genitalia in ¢ dark, not prominent, bluntly conical, with a few hairs; 
in @ the ovipositor is subeylindrical, pale yellowish, with two stiff hairs 
at tip. 
Legs.—Pale dirty yellow, minutely pubescent. Coxae with some strong 
black bristles at tip. Femora without distinct bristles, the hind pair 
are often paler in colour, and are generally blackish towards the tips, 
often only very slightly so. Tibiae with a distinct row of short bristles 
on outer side, the four posterior tibiae with two terminal spurs, the hind 
pair having a close row of very minute hairs on the outer side, adjacent 
to the row of bristles. Tarsi slightly blackish. 
Wings.—Pale yellowish, a little iridescent, costal border shortly bristly 
with two divaricating rows as far as the tip of the 3rd longitudinal vein, 
which, shortly forked, reaches about the middle of the wing, the 1st 
longitudinal ending just beyond the middle of the costal cell. Of the light 
veins, all of which attain the wing-margin, the 1st takes a single, distinct 
curve upward, the 2nd and 8rd are moderately bisinuate (sometimes much 
less so), the 4th is nearly straight. Halteres pale yellow. * * * 
Note.—This species is very variable in colour, ranging from bright 
ferruginous to grey, the proportion of black on the abdomen totally altering 
the general appearance of the insect. The species, however, once well 
understood, is tolerably easy to recognize. 
Concerning the life history of Aphiochxta ferruginea, Bru- 
netti’s (39) notes showed that it required a period of from twelve 
to fifteen days for the first generation to emerge. Pupation 
occurred from five to eight days after the eggs were laid. Emer- 
gence of the imagines took place seven days after pupation. 
As the eggs were not noted at the time they were laid, there 
is a variance of three days in the process. 
The first generation laid eggs when they were five or 
six days old. Three days after pupation a few imagines 
emerged. Due to the scarcity of food the majority of the second 
generation emerged from sixteen to twenty days after the eggs 
were laid. 
The specimens of flies which were secured and employed in 
the experiments outlined in this paper were compared with the 
identified specimens in the Bureau of Science collection at Ma- 
nila by Prof. Charles S. Banks, and were found to correspond 
with Aphiochzta, ferruginea collected by him. There is, also, 
a correspondence with the description given by Brunetti. 
Before going into detail concerning the object of the experi- 
ments in this paper, a review of the literature will be gone 
into concerning the phenomenon of the larve of dipterous insects 
transferring pathogenic bacteria from the medium upon which 
