MOSQUITO CONTROL

Evening Post, Volume CVI, Issue 126, 24 November 1923, Page 24

MOSQUITO CONTROL

FIGHTING THE PEST WITH

MINNOWS

ATTACKING THE LARVAE.

The uss of fish to destroy the larvae of the mosquito in waters where they breed has been, often advised and employed to some extent (says the "Literary Digest"). A minnow especially adapted to this use, being Vigorous, prolific, and very hungry for mosquitoes, is now bred on a large scale in Cali^ fornia, and it is hoped that its use may relieve mosquito-ridden communities where for any reason crude oil or other means of fighting the pest are not available. _ Louva> G. Lenert, sanitary engineer in' charge of mosquito control for the Board of Health of that State, has an article on the use of this minnow in its "Weekly Bulletin" (Sacramento). Mr. Lenert writes as follows : — " 'Gambuaia affinis' is the name given to a small, surface-breeding top-minnow whose native home is in the eouth-east-ei-n part of the United States, ranging from New Jersey southward along the Atlantic seaboard and westward along the entire Gulf coast and as far as Del Rio, Texas, near'the Mexican border. It is also found as far north as Tennessee and Missouri. In the South it is frequently spoken of as the 'pot-belly.' "It is well that its name was decided upon before its economic value was learned, otherwise we might have been confronted with a name a yard long, in which an attempt would bo made to describe its true worth. There is no way ,in which this could be estimated, but in a small way it can be said to be worth many millions to the Southern States.

"It feeds largely upon insects, and ■wherever it inhabits water in which mosquitoes breed its principal food consists of mosquito larvae. For the destruction of mosquito larvae it has been found superior to any other species. Because of its small size it is able to penetrate to very Shallow 'depths, where it is freo from the attack of predacious fishes. Great numbers are often found in waterless than-an inch in depth. 'In fact, conditions which are idealfor mosquito propagation, are usually also suited to 'Gambusia affirms.' It seeks its food at the surface, ■ along the edges of ponds, in the marsh grass and swamps, where it is also protected from large fishes. It is not often found in the open waters where, game fish are present. ' ' ■■■ -■ ■ -

"This fish is vigorous and very hardy! It requires no special environment for spawning, the young being in an' advanced state of development at birth. It is very prolific, producing as many as six to eight broods in a season, and averages forty young to a brood. ■ Three generations may' be represented in a single .season. At birth these. minnows are approximately one-half inch in total length, and they have been observed to begin their' life of lirvae; destruction when not more than one day old. "Because of its extreme prolification, easy propagation, ability to adapt itself to different conditions, and to reach areas not penetrated by other species, exceptional devouring capacity, -general habits and liv'iag in identical areas with mosquito larvae, 'Gambusia anW is the most valuable natural agent known for the abatement o! mosquito-breeding. "As a control measure these minnows may be introduced in stock ponds, cisterns, shallow we.lls,. water-troughs, surface- reservoirs, irrigation canals, and similar places where oiling or draining proves impracticable. They are especially useful in the suppression of mos-quito-breeding in slowly-moving streams, sloughs," and pot-holes 'in drainage channels.

"The question is often asked why, with such a, valuable ally, mosquitoes continue to exist in the' Southern States ferfect mosquito-control cari be secured in any body of water by planting 'Gambusia affins' therein, provided the area is hrst properly conditioned. ; "Nature's protection of mosquito proauction consists of algae, drilt, debris, and aquatic or other dense vegetation. Clean edges and . surface free of debris and floating vegetation are of prime importance. Erect vegetation, such as cat-tails, when not too dense, will not prevent the penetration and control of mosquifo-breradirig by these minnows, bumciently clear, shallow ' edges are necessary asa protection from game fish when present. ... "Local 'hatcheries' are desirable in every;,locality' where the use of 'Gambusia affims' is anticipated. These should be, preferably, rather small ponds containing some plant growth free from the natural enemies (game fish water snakes, water fowls, bait collectors, etc.)'of the minnows, and situated where they will be easily accessible by a-utomobile or wagon. Only under very exceptional circumstances ?-V,t ■ t>e, found necessary .to feed them. ■'• S'? • *afc- evefy weapon known might _be put to use in the control of mosquitoes in California, the- State Board of Health in April, 1922, secured a shipment of 'Gambusia affinis' from lexas, and established a hatchery in wha£ ,s known as the'lily pond at Slitter s Fort, Sacranunto. Since that date local hatcheries have been established in Redding, Anderson: Los Molinos, Oroville,- Meridian, Bakersfield,' .and Los Angeles.' The stock on hand for this purpose now is almost unlimited. Many communities will' avail' themselves of this opportunity of securing a start for their local, 'hatchery.' "Nature's balance must be rememberea at all-times, however, and the fact kept in mind that these finny, friends can only be counted on for perfect results when proper conditions are met with. They cannot accomplish miracles and will; never entirely replace the ditching, cleaning, brushing, and. oiling work necessary in every welUorganised mosquito-control; programme."