The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1901-09-20

NH R. D. L. vANDINE, one of the
HA new teachers in the Normal
School, has made an interesting
s: udy of mosquitoes, and series of
experiments which he describes as fol-
lows:
Standing under a water tap in a
dooryard in this city, was an ordinary
tub, about two feet in diameter, nearly
full of water From a passing glance
| the water could be seen to contain
''wrigglers" of the young of the mos
quito. A more careful observation
disclosed the fact that the water was
swarming with the creatures in stages
more or less developed. The contents
of the tub were emptied on the ground,
thus preventing further development.
| In this same yard was small pool
about six feet square and something
over one foot in depth, in which va
rious aquatic plants were growing. A
| similar condition was found there in
regard to the presence of Inc larvae of
the mosquito. A very low estimate
would place one larvae for every cubic
| inch of water. This means that the
small pool contained over $4,000 young
| mosquitoes, about to issue into the
adult state. A small quantity of coal
oil was poured on the surfaca of the
water. 1t spread quickly over the sur
face, and the pool when examined two
days later was free from the larvae.
The tub and pool together contained
about SlXty-fiye thousand larvae of the
mosquito. 1t sounds large, yet the
simple act of emptying the contents of
the tub and pouring. a small amount of
oil (about two ounces) on the surface
of the pool lesSened the number of
mosquitoes In that vicinity by $4,000.
The plants We're not injured.
The following work was carried on
/ before the Normal School students
along with their nature study work:
The eggs from eight females were
placed in feeding jar. From these
; were obtained on Matching about fif-
arranged, and one-half the larvae was
placed. in each jar. One breeding Jar
was left undiSturbed. All of the larvae
lived and changed into the pupae.
Some of the pupae We're allowed to is
sue into the adult mosquito in order
to obtain complete life history. On
the surface of the water in the second !
breeding jar some coal oil was pour
ed. The amount was very small, but
1t quickly spread over the surface of
the water. In fifteen minutes fully
one-half the larvae were at the sur I
face, not breathing as usual, but dead.
AS they rose to the surface to obtain
air, their breathing tubes or respira-
tory syphons came in contact with the
oil. This caused them to move quickly
beneath the surface, only to return
soon in a vain attempt to secure air.
Failing to do So they were forced to
take the oil, which caused their death.
A few were able to remain beneath the
surface for some time, but sooner Or
later they were forced to seek the top
for air, and met, the fate of their conf
panions. The jar was examined later
in the day and did not contain a single
living larva.
LIFE HISTORY OF THE MOSQUITO.
The eggs of the mosquito are laid in
a raft-shape mass by the female at
night on the surface of water. The
mass contains several hundred eggs,
and all together Is about one-fourth of
an inch in length. The places selected
for depositing the eggs are such places
as vessels in which water has been
left standing, ponds, bitches, swamps,
water tanks. etc. The eggs under IA
vorable conditions hatch in one days
time. The larvae require about a
week for growth. The pupal stage fol-
lows, which Is much shorter, the adult
issuing In two or three days. The lar
vac, although aquatic, require air, and
must therefore come to the surface.
They breathe by means of tube sit {
uated near the edge of the abdomen.
which they extend up through to the
air while resting at the surface with
the head in downward position The
air Is drawn through the breathing
tube which leads into branched ira
chael tubes running through the body.
H.
ner, with the exception that they pos
sess two tubes instead of one, situated
not at the caudal end of the body, but
arising from the thorax. The natural
enemies of the larvae and pupae are
other aquatic insects and fishes. Birds
and other insects prey on the adult to