Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-09-21

because they are shut of from the sea
and polluted with sewage, have sunk TO
a level considerably below mean high
tide, rendering their drainage by grav-
itv irnDracticable. Thus the ordinary
methods used for mosquito drainage on
the marshes as nature made them have
been rendered impracticable over con-
siderable sections Of this area.
OF value in the fight on the mosquito
are the insects own enemies. The eggs
of the salt water variety are in the
marsh mud, and every time the mead
ows are covered with the warm water
of Summer either by tide or rain, a
brood of wriggles Immature forms Of
the mosquitoes) matches and within two
weeks the insects are on the wing.
Two natural agencies limit or entirely
eliminate the broods thus started. II
the weather is bright, tn shallow sheet
water covering large areas of marsh
surface and filling the shallow pools is
quickly evaporated and the wrigglers
die. The deeper pools harbor small
killifsh, which eat all wrigglers that
appear. The result is that compare
, lively few mosquitoes get on the wing
II, however, the weather is clouG. and
the atmospheric moisture high, the sheet
water disappears very slowly and an
enormous brood of mosquitoes may es-
cape.
Trenches Recommended.
| In view Of the fact that the salt
marsh surface normally about foot
above mean high tide, it Is clear that
trenching will ordinarily remove all
sheet water and empty shallow pools.
! In a few isolated localities it has been
/. found more effective to fence the tide
than n &c RI pYff largo outlets nnCpg-
| sary to get rid of tide water.
! The State Experiment Station, under
/ laws enacted in 1905, has been draining
the salt marsh as rapidly as the funds
/ granted by the Legislature would per-
/ init, and in addition has furnished I'M
der the terms of that act advice and
:! plans for much locally supported work
in both the salt and fresh varieties.
At the present rate CT drainage, less
than 10000 acres year (of which the
State now does only Is per cent?, 1t is
estimated that only five years Will be
required for the v1rk.
While the bulk Of the battle is d.
rected at the salt marsh mosquito, be-
cause of its tremendous effect, cam
paign is being wagoi to rid the State
of the fresh water pest. Application OF
chemical solutions Is the principal
means used to combat the latter variety.
Experts Define Pests.
State experts hs-' put the fresh water
species into several classes and deter
mined the vulnerable elements OF each
These follow:
House qLito.-Find all water IN
which 1t breeds, and make 1t unnt for
such by draining, filling, stocking. with
fish, or the application Of oil or larVi'
eide.
Malarial Group Practically same az
house type.
Swamp Mosquito Group.-The control
of this group differs from that OF the
, other groups, and drainage must neces'
sarily play large part. Breeding occurs
/ ov large areas where larvicide is onll
! slightly effective. Furthermore, the. egg
could not be killed of with oil because
, they do not come to the surface. Moth
ing but a substai t mixes In TIT
! water can be successfully used. TIL
/ type of inspection necessary to mt
breeding OF this species is radically dif
ferent. The tussocE forming grasse
: growing in unsupported places must D.
a pulled up in the search for the larvae
a fastened to the roots. Sometimes tn
e larvae can be scraped of the mud Will
: a dripping net, after the tlissock gra&
e has been pulled away.
d Woodland pool mosquito group
These pools are usually oiled in tn
], Spring Just before the pests are read