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3. The Nymphae are not so dark as those of 0. Fatigans ; the trumpets
are expanded and broadly triangular in shape. They hatch out within 2 to 4
days invariably and never more.
4. The Imago varies in size from 2.5 to 4 m.m., the smaller size
predominating. Their colour for a day or two of their emergence is bright red
on the thorax, with white bright lines. Of these there are two median parallel
pale lines, and two curved silvery ones, one on each side and a small line in front
between the two median ones. The legs are banded and on account of their
striped appearance they are known as tiger mosquitoes. The colour gradually
darkens to reddish brown, though it is never so dark as it is in Bombay. They
bite viciously during the day from 11 a.m. to 3 p.m., and the bite is very
irritating. I have never found S. Fasciata to become a nocturnal feeder after
its first blood meal. Dark clothing attracts them most. Adult S Fasciata
were almost always caught inside the houses and out-houses, but never outside
or in gardens. The males are more delicate in structure and smaller in size
and from any particular sample more males than females hatched out.
5. The eggs are ovoid, pointed at one end and rounded at the other,
and are surrounded by a series of little air chambers. They adhere to the sides
of the vessel or to the material on which they are laid, and are difficult
to remove.
6. Life History.—The following points in their life history were noted.
Three series of cage experiments on isolated couples were done; (the cages used
were 1 cubit feet in size, were made of wooden frames with fine cloth gauze
stuck all round. They were well protected from spiders or ants. The mosqui-
toes were fed on black raisins, and a dish of water with pieces of pith floating
was kept in).
In the 1st series, where no feed of blood was given, no egg-laying was ever
seen, though mating was often noticed.
In the 2nd series, the couples were fed on blood on the first day of their
emergence, and subsequent feeds were given ten days after the last batch of
eggs was laid. This period was allowed to elapse in order to observe whether
one feed of blood was sufficient for the egg-laying function for all their life.
Copulation was not seen earlier than on the third day, and on the sixth day or
later, the first batch of eggs was laid, the number of eggs varying from 24 to
44; in a few cases a second and a third batch of 8 to 12 eggs was laid in two or
three days more. Similar results were noted after the 2nd and 3rd feed of
blood ; but the female never outlived the 3rd egg-laying period., the maximum
number of eggs laid during the lifetime of one female being 64.
In the 3rd series, it was attempted to give the female frequent feeds of
blood. In the majority of cases she refused to bite and the results in no way
differed from that of the second series.
The males died off earlier than the females, 12 days being the maximum
period of their lifetime. New males were always supplied. The female lived
from four to five weeks.
The eggs were laid singly during the night time and some of them
immediately sank though an almost perfect rim of floats could be seen around
them. 25 per cent. of them hatched out during the first 24 hours ; but even after
three days 20 per cent. still remained unhatched. These unhatched eggs, after
remaining in water for a fortnight, were dried and a few days later were placed
under suitable conditions for hatching. Out of these only a few hatched out at
different times during these three months, but the others, 8 per cent., are still
just the same. Whether they are unfertilized eggs, or some form of resistent
eggs, I cannot say. Another batch of eggs, which were dried soon after being
laid, were after three months placed under suitable conditions and these hatched
out with the above reservations.
No statement can be made as regards the seasonal variation of S. Fasciata
in the same locality, nor of their prevalence in different parts of the city at any
one particular period.