M 161
Certain entomological specimens (weevils found in rice and flour) were submitted by the M.O.H. They were identified as belonging to the genera Sitophilus, Tribolium, and Gnathocerus, and forwarded to Professor Patton, Liverpool School of Tropical Medicine, who confirmed them as Sitophilus oryzoe, Tribolium confusium, and Gnathocerus maxillosus.
(h) EXPERIMENTS WITH PARIS GREEN.
Paris Green was obtained from the Chinese Export, Import and Bank Company, Ltd. Visits were paid to the P.W.D. quarry at North Point and to the Green Island Cement Company in order to select a diluent. Cement dust was decided upon—the Green Island Cement Company supplying it free of charge. Owing to the fineness of the dust it was not considered necessary to put it through a sieve.
A mixer was made by the South China Motor Ship Building and Repairing Works, Kowloon, according to plans supplied.
On 15th August Laboratory trials were made with a 1% dilution. Four dishes A, B, C, D containing 10, 10, 10, 12 large larvae were placed in the verandah of the Laboratory, at distances of 10', 12', 14', 16' from a chalked line. A small handful of the mixture was scattered in the direction of the dishes—the sower standing at the mark. At the end of three hours all the larvae in dishes A, B, C, were dead and nine in D. In 4 hours the remainder were dead.
On the 22nd August a fallow rice plot 16' by 45' was dusted by hand with a 1% solution. Before dusting it was ascertained that large Anopheline larvae could be obtained without difficulty. Next day a search was made over all the plot by the Medical Officer Shing Mun and the Malariologist, only 2 large larvae and 9 small ones were collected. Meanwhile a Paris Green "Duster," 2 "Guns" and soapstone diluent had been obtained from India. On the 20th October a stream at Pokfulam was visited, a pool about 6 feet square was selected and all the Anopheline larvae collected. Water was flowing slowly through the pool, the larvae were put back—also others which had been collected elsewhere, numbering in all 65. A 1% mixture was sprayed by the Duster—5 hours afterwards 34 were recovered—13 of which were dead. It is possible that other dead larvae had been carried away by the slow current. Of the 21 live ones recovered the majority were small. A breeze was blowing and it was difficult to distribute the mixture satisfactorily owing to the presence of eddies. On 16th November a plot of 25' by 21' which had been used for growing vegetables, but at that time contained water and grass, was sprayed with one of the "Guns" and a 1% soapstone mixture. Numerous large Anophelines larvae were demonstrated just before spraying. Afterwards the place was well searched. One large larva was found alive and 21 dead. Quite small larvae have been killed in the Laboratory with these mixtures. It is hoped to experiment further with rice fields and fallow rice fields.
Five hours
Page 525
Page 526
M 161
Certain entomological specimens (weevils found in rice and flour) were submitted by the M.O.H. They were identified as belonging to the genera Sitophilus, Tribolium, and Gnathocerus, and forwarded to Professor Patton, Liverpool School of Tropical Medicine, who confirmed them as Sitophilus oryzoe, Tribolium confusium, and Gnathocerus maxillosus.
(h) EXPERIMENTS WITH PARIS GREEN.
Paris Green was obtained from the Chinese Export, Import and Bank Company, Ltd. Visits were paid to the P.W.D. quarry at North Point and to the Green Island Cement Company in order to select a diluent. Cement dust was decided upon- the Green Island Cement Company supplying it free of charge. Owing to the fineness of the dust it was not considered necessary to put it through a sieve.
A mixer was made by the South China Motor Ship Building and Repairing Works, Kowloon, according to plans supplied.
On 15th August Laboratory trials were made with a 1% dilution. Four dishes A, B, C, D containing 10, 10, 10, 12 large larvae were placed in the verandah of the Laboratory, at distances of 10', 12', 14′, 16′ from a chalked line. A small handful of the mixture was scattered in the direction of the dishes the sower standing at the mark. At the end of three hours all the larvae in dishes A, B, C, were dead and nine in D. In 4 hours the remainder were dead.
On the 22nd August a fallow rice plot 16′ by 45' was dusted by hand with a 1% solution. Before dusting it was ascertained that large Anopheline larvae could be obtained without difficulty. Next day a search was made over all the plot by the Medical Officer Shing Mun and the Malariologist, only 2 large larvae and 9 small ones were collected. Meanwhile a Paris Green "Duster," 2"Guns" and soapstone diluent had been obtained from India. On the 20th October a stream at Pokfulam was visited, a pool about 6 feet square was selected and all the Anopheline larvae collected. Water was flowing slowly through the pool, the larvae were put back-also others which had been collected elsewhere, numbering in all 65. A 1% mixture was sprayed by the Duster "-5 hours afterwards 34 were recover- ed 13 of which were dead. It is possible that other dead larvae had been carried away at the slow current. Of the 21 live ones recovered the majority were small. A breeze was blowing and it was difficult to distribute the mixture satisfactorily owing to the presence of eddies. On 16th November a plot of 25′ by 21′ which had been used for growing vegetables, but at that time contained water and grass, was sprayed with one of the "Guns and a 1% soapstone mixture. Numerous large Anophelines larvae were demonstrated just before spraying. afterwards the place was well searched. One large larva was found alive and 21 dead. Quite small larvae have been killed in the Laboratory with these mixtures. It is hoped to experiment further with rice fields and fallow rice fields.
"
Five hours
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