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Borax as a larvaecide
1915.
P U B L I C H E A L TH. infect such insect host. Our experiments were, therefore, based on the hope that no such further development of the embryos occurred in the bovine host.
Experiments to Test the Length of Life of Embryos Ingested by Slomoxys Calcitrans. From May, i912 , to December, z912, a large number of Stomoxys calcitrans were caught, chiefly at the abattoirs at Glebe Island, Sydney, and kept in fly-proof cages. The flies were as soon as possible fed on fresh worn-nests obtained from the abattoirs, which were cut open and placed in watch glasses in the cage. If the insects were replete with blood few of them would immediately feed upon the worn-nests, t~owever, upon starvation for ~4 hours, they readily flew down upon and ingested the juice from freshly-opened nests. Having obtained their fill .in this way it was necessary to keep the insects alive as long as possible on blood. They were therefore fed in the majority of instances daily upon guinea-pigs. On these animals they fed well, and though there was a heavy mortality from confinement, a fair number of flies lived several days, one even as long as eighteen days. This feeding upon guinea-pigs' blood suggested naturally the possibility that such blood might i n j u r e embryo worms which had been ingested, whose natural habitat was in the tissues of the ox and of some insect feeding on the ox. In one or two instances flies were fed for several days on an ox, but in the ordinary course of events this practice: was not possible, Living embryos were found on several occasions in flies one day after feeding on an open nodule, in one case nine or ten living embryos were found in a fly two days after thus feeding, and in another instance about 6o live embryos were found three days after feeding. In those flies which survived longer periods, living e m b r y o s were not found. TOe search for living embryos was made by carefully teasing the various parts of the fly in normal saline solution, and then examining under the microscope. It is possible, of course, that embryos, quiescent and undergoing g r o w t h , escaped detection amongst muscular masses, etc., in the careful search that was made. The small number of flies which survived a period of a week, during which some development might have
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occurred, must also be considered. It would appear from these experiments that Stomoxys calcitrans can ingest living embryos of O~dwcerca gibso~i, and that these may ba found alive in some instances within the fly for as long as three clear days after ingestion. Thereafter, however, they have not been found alive, though in one case five days after feeding embryos enclosed still in the egg were noted. The fact that living embryos could be found in Stom,oxys calcitrans, up to three days after ingestion, is allied to the question as to whether they can exist for such a period of time in other flies. A few experimental investigations on Muses do~l,s~tica and Mttsca vetustissim~ are referred to. Though dead embryos could be found with ease in flies which were fed one or two days previously on worm-nests, no living embryos were detected. Though the experiments are few they would seem to suggest that the embryos found a more congenial medimn in the alimentary canal of Sto~hoxys valcitrans than in that of the other two species. B O R A X AS A L A _ R V A E C I D E . UST as all rational mosquito extermination work aims to prevent the breeding of these pasts, so work directed against the extermination of flies should be directed principally against fly breeding. It is now well established that the house fly breeds mainly in horse manure, though if this is not available garbage and other refuse are made to serve the purpose. The United States Department of Agriculture has recently carried on a series of tests to discover a method of treating manure so as to kill fly larvae. Among the substances tested were kerosene, iron sulphate, potassium cyanide, formaldehyde, calcium cyanamid, pyroligneous acid, common salt, copper sulphate, lime-sulphur mixture, Paris green, sodium fluorid, several proprietary disinfectants and borax. In passing on the utility of the substances mentioned three factors were considered essential i--z, destructive action on fly larvae ; 2, non-injurious effect on manure : 3, lack of extremely poisonous properties. By far the most effective, economical, and practical o l a f [ the substances tested is borax in the commercial form iu which it is available throughout the country. In using borax as a ~arvaecide the following general directions shoulu be observed. Apply one pound of borax to every 12 bushels (t 5 cubic feet) of manure immediately on its removal from the barn. The borax should be applied particularly around the outer edges of the pile with a flour sifter or other f i n e sieve, after which two or three gallons Of water should be sprinkled over the borax-treated manure. Those desiring to learn further details of this method of killing fly larvae are referred to Bulletin No. 118, United States Department of Agriculture, July I4th, ~9r4 .
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P U B L I C H E A L TH. infect such insect host. Our experiments were, therefore, based on the hope that no such further development of the embryos occurred in the bovine host.
Experiments to Test the Length of Life of Embryos Ingested by Slomoxys Calcitrans. From May, i912 , to December, z912, a large number of Stomoxys calcitrans were caught, chiefly at the abattoirs at Glebe Island, Sydney, and kept in fly-proof cages. The flies were as soon as possible fed on fresh worn-nests obtained from the abattoirs, which were cut open and placed in watch glasses in the cage. If the insects were replete with blood few of them would immediately feed upon the worn-nests, t~owever, upon starvation for ~4 hours, they readily flew down upon and ingested the juice from freshly-opened nests. Having obtained their fill .in this way it was necessary to keep the insects alive as long as possible on blood. They were therefore fed in the majority of instances daily upon guinea-pigs. On these animals they fed well, and though there was a heavy mortality from confinement, a fair number of flies lived several days, one even as long as eighteen days. This feeding upon guinea-pigs' blood suggested naturally the possibility that such blood might i n j u r e embryo worms which had been ingested, whose natural habitat was in the tissues of the ox and of some insect feeding on the ox. In one or two instances flies were fed for several days on an ox, but in the ordinary course of events this practice: was not possible, Living embryos were found on several occasions in flies one day after feeding on an open nodule, in one case nine or ten living embryos were found in a fly two days after thus feeding, and in another instance about 6o live embryos were found three days after feeding. In those flies which survived longer periods, living e m b r y o s were not found. TOe search for living embryos was made by carefully teasing the various parts of the fly in normal saline solution, and then examining under the microscope. It is possible, of course, that embryos, quiescent and undergoing g r o w t h , escaped detection amongst muscular masses, etc., in the careful search that was made. The small number of flies which survived a period of a week, during which some development might have
95
occurred, must also be considered. It would appear from these experiments that Stomoxys calcitrans can ingest living embryos of O~dwcerca gibso~i, and that these may ba found alive in some instances within the fly for as long as three clear days after ingestion. Thereafter, however, they have not been found alive, though in one case five days after feeding embryos enclosed still in the egg were noted. The fact that living embryos could be found in Stom,oxys calcitrans, up to three days after ingestion, is allied to the question as to whether they can exist for such a period of time in other flies. A few experimental investigations on Muses do~l,s~tica and Mttsca vetustissim~ are referred to. Though dead embryos could be found with ease in flies which were fed one or two days previously on worm-nests, no living embryos were detected. Though the experiments are few they would seem to suggest that the embryos found a more congenial medimn in the alimentary canal of Sto~hoxys valcitrans than in that of the other two species. B O R A X AS A L A _ R V A E C I D E . UST as all rational mosquito extermination work aims to prevent the breeding of these pasts, so work directed against the extermination of flies should be directed principally against fly breeding. It is now well established that the house fly breeds mainly in horse manure, though if this is not available garbage and other refuse are made to serve the purpose. The United States Department of Agriculture has recently carried on a series of tests to discover a method of treating manure so as to kill fly larvae. Among the substances tested were kerosene, iron sulphate, potassium cyanide, formaldehyde, calcium cyanamid, pyroligneous acid, common salt, copper sulphate, lime-sulphur mixture, Paris green, sodium fluorid, several proprietary disinfectants and borax. In passing on the utility of the substances mentioned three factors were considered essential i--z, destructive action on fly larvae ; 2, non-injurious effect on manure : 3, lack of extremely poisonous properties. By far the most effective, economical, and practical o l a f [ the substances tested is borax in the commercial form iu which it is available throughout the country. In using borax as a ~arvaecide the following general directions shoulu be observed. Apply one pound of borax to every 12 bushels (t 5 cubic feet) of manure immediately on its removal from the barn. The borax should be applied particularly around the outer edges of the pile with a flour sifter or other f i n e sieve, after which two or three gallons Of water should be sprinkled over the borax-treated manure. Those desiring to learn further details of this method of killing fly larvae are referred to Bulletin No. 118, United States Department of Agriculture, July I4th, ~9r4 .
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