Evening bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1895-1912, 1904-01-09

It will be seen that the larva Is hcay.
Ter than watC since II will sink To
the bottom without effort. hut must
make a vigorous effort To- gain the sur
face. It is interesting to study out
why the larva can remain motioulcss
at the surface since the body is heav.
Ter than the water. The breathing
tube is so constructed that on being
extended to the air II expands over
the surface Of the water aud the ten.
sion Of the surface film supports the
body. II the young larvae are tso
weak to swim to the surface or If. for
any reason, they cannot obtain the
air, they drown since In no other man.
ner can they breathe. This fact is of
great Importance In the destruction Of
the pest since, by covering the surface
witlLsa film of coal oil they are pre-.
vented fpm breathing the air and
also any mosquitoes either emerging
from the water or coming to deposit
their eggs are killed by contact with
the oil. The destruction of larvae by
oil can be easily demonstrated.
The Pupae.
In the course OF development the
wrigglcrs or larvae transform to pn
pac, which Is simply another stage In
the lifc.history OF the mosquito. Inc
length oil the lar'al iiie shouid nave
been determined In the former obser.
vations. In the pural stage the mos
quito is easily recognized ny us pecu-
liar structure anu habhs.
The pupa rests usually az the sur
face, IN quiet position. anu IL u'sun-
guished by Its large head. This Is real
ly the head and that portion OF tho
body to which the wings ana legs OF
adult insects are attached, known AS
the thOrax, together with the Dody or
abdomen curved beneath IL. Inc pu
pa moves when disturbed as matter
OF prVtectioh. II does not increase IN
size or take FOOD, this oeing SIMPLY
more or less Inactive period during
which the mosquito changes 10 inc
adult.
The pupils will have no difficulty In
describing the difference between the
larvae and pupac In regard to the man.
} ncr In which they move about. the
resting position at the surface, and the
density Of the body as compared with
that of water. The pupa swims, not
/ by twisting the body or abdomen from
, side to side. hut by the aid of two
flaps at the end OF the abdomen aud
, doubling together In a peculiar man
ncr It's resting position at the surface
Is not head downward but with the
. tail end of its body down. Further.
more, air Is obtained by means Of two
tubes extended from the upper side of
the thorax. These parts can be more
clearly seen and drawn by aid Of u
| hand lens.
7 The Full.Grown Mosquito.
: The most interesting part In Tn,
lifc.history " the mosquito is the tim,
when IL energies from the pupal skin
Y an adult insect with wings and legs
b. This change should be carefully watch
Il ed for and will occur two or three day
n after the larva has changed to the ~
q pa. The outer covering splits length
C wise on the upper side Of the thora
Z and through this opening tho Dios,iu
=. Ia. slowly pulls itself, the pupal ski
n acting as raft on the water. II wi
L. lie easy for the students to observ
n. this process carefully and relate jus
~ how II occurred. II should be emph'
"a sized that with change Of csvirol
IL mcnt aud habits Of life come also
lc change of structure to ~ the new col
lg ditions.
h. will mention but one other point