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mile away.
Hill streams, paddy fields, seepage areas, irrigation channels and swampy areas were situated in its immediate night- bourhood. The fauna of the district were A, mingulatus, A. menimus, A. hyreams, A. Jeyporiensis, A. tessellatus, A. splendidus, A. Karwari, C. tritaeniorhynchus, C. latueniorlyn- chus, C. whitmuuri, C. vishmi, M. uniformis, etc.
Que of the windows at the side of the hut was taken off, and it was replaced with a window-trap, which consisted of two parts. The top part was a lax of wire gauze on wooden Trameworks having a sliding panuel at the bottom to allow an entrance slit for the entry of mosquitoes and to close the slit when the box was relnowed in the murning. The bux served as a holding-cage for the observation of mortality of mosquitoes that eutered the box during the period of observation. The lower part was a supporting wooden framework mounted with wire gauze, and it was fitted to the window frames. All the other windows were fitted with black cloth curtains, so that the windows could be closed completely when required.
The human bait during the course of observation con- sisted of two caretakers of the Water Works, one trained assis- tant and one Inspector. On the 17th October, a probationer Malaria Inspector was sent there for training.
the report.
The following is a brief summary of the full text of
The points to be determined were:
1. The time of entry of the mosquitoes and their
relating to time of biling.
Both Anophelines and Culicines entered dwellings at and after dusk, and they continued to enter dwellings at various times throughout the night with a peak period of entry from 8.30 p.m. to 10.30 p.m. (Hong Kong summer time) Mosquitoes that entered the dwellings fed on the inmates at various times throughout the night, and the peak period of biting coincided with that of the entry. The peak period of entry and biting was prolonged on still sultry nights. There were marked differences between re- lative attractiveness of different individuals used as huruan bait. This preference maintained its existence throughout the period of the observation.
2. The resting position in relation to doors, walls,
windows, ceiling etc.
On 12 nights, observations were made with regard to the resting positions of mosquitoes. Mosquitoes found resting in the hut were segregated into those caught on walls, roof, screen of windows and on furniture. Of 588 anophelines caught, 113
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were found on walls, 410 on roof, 45 on screens and 15 on fur- niture. Their resting positions are of great importance in con- sidering the application of insecticide to dwellings.
3. The length of the resting period of individual
species.
There were as many na seven species of anophelines coming into the hut. To separate them into individual species when they were resting in the hut at night was impracticable. They were, therefore, segregated into large and small species. The large species represented A. hyreanus var. sinensis, and the small species represented A. minimus, A. jeyporiensis var, candidiensis, A. karwari, A. tessellatus, A. maculatus and A. splendidus. The minimum length of the resting period of the large species was three minutes for the fed and half-a-minute for the unfed, while the maximum length of the resting period of the fed and the unfed was 272 minutes and 89 minutes respectively. With re- gard to the small species, the minimal length of the resting period of the fed and the unfed was 2 minutes and half-a-minute and the maximal length of the resting period of the fed and the unfed was 206 minutes and 44 minutes.
4. Observed death rate before and after residual
spraying.
Before the residual spraying, only one A. hyreanus var. sinensis and one A. karwari Q, both unfed and dead, were discovered on the floor in the but in an observation period of 14 nights, where- as 791 anophelines were collected on the floor in the same hut in an observation period of 55 nights after the residual spraying. Of 791 anophelines collected, 364 were A hyrcanus var. sinensis; 266, A. jeyporiensis var. candidiensis; 14. A. minimus; 21, A. maculatus; 106, A. karwari; 12, A. splendidus and 8, A. tessel- latus.
5. The effect of "Gammexane" in these observed
habita.
After the application of "Gammexane" Dispersible Powder, a marked reduction in number of mosquitoes was observed in the but for 7 nights, but mosquitoes, such as A. hyreanus, A. kar- wari, and A. jey poriencis var. candidiensis, nevertheless, entered the treated hut and fed on the inmates as early as the 1st night following the spraying. On the 15th night, the number of mos- quitoes entering the hut and feeding on the occupants was as numerous as before. During the first 14 nights after treat- ment, mosquitoes were found restless after making contact with the treated surfaces, and short flights from one spot to another were noticed. This was markedly demonstrated in the 1st week;