29
malarial carrier of the Punjab, is also rare. N. stephensi, a common
Indian species, has never been found by us in the Duars.
Myzomyia listoni.-This is the most important species present,
and the one most frequently met with in dwellings. Its larv are
especially abundant in running water, especially in the little boulder-
strewn streams where water continues to trickle for some time after
the cessation of the rains. They are found congregated in the shelter
of boulders, or lying in little pools and nooks at the edges of the bank,
and in the largest numbers where a few blades of grass project into
the water. They may be found also along the edges of streams
of considerable volume, even where there is no grassy or weedy growth
to shelter them, in quiet portions where the current is broken by the
presence of large boulders. Very often they occur in large numbers
among the pebbles where the water is in such small amounts that it
cannot be dipped out until a small pool has been formed by the re-
moval of a few stones.
The adults can travel considerable distances and can rise several
hundred feet. High bluffs overlooking swampy country are often
infested with this species. They can exist through many months of
drought and may be found when it is difficult to determine the breed-
ing places from which they have originated.
Nyssorhynchus theobaldi.-Like M. listoni this species is also a
stream-breeder, but its larv are found most frequently in the small
pools left during the drying up of the stream beds after the rains.
Like the larv of M. listoni its larv, especially the larger ones, may,
when disturbed, sink to the bottom of the water and remain there
for long periods. We have frequently obtained thirty or more speci-
mens from a small pool a foot or so square by stirring up the bottom
and then waiting patiently for them to appear; in such cases an ordi-
nary cursory examination might have led us to conclude that no
larv were present.
The adult is a strong flier and may be found in dwellings far
from its breeding places.
Pseudomyzomia rossi.-This species breeds in the Duars in buffalo
Wallows, rice-fields, and small surface pools on roads and in lines.