M 138
(a) INVESTIGATION OF SPECIES AND THEIR LIFE HISTORIES.
Anophelines.
The number and species of the various anopheline larvae examined are given in Table I. Table II gives the number and species of the imagines obtained from pupae collected, and from pupae obtained from the larger larvae.
An experiment was performed in order to obtain an approximate estimate of the number of days which Anophelines might live, if unable to leave a dwelling, and if only blood meals were available. On the 23rd October a batch of Anophelines consisting of 4 A. hyrcanus, 1 A. maculatus and 1 A. minimus which had recently hatched out in the laboratory were transferred to a lamp glass whose ends were covered with mosquito netting. The mosquitoes were allowed access to raisins and damp lint was placed on the top of the netting. At 8 a.m. on the 24th the lamp glass was applied to an arm and 1 A. hyrcanus fed. The raisins and water were withheld but a blood meal was afterwards offered daily at 8 a.m. On the 25th 3 A. hyrcanus fed; on the 26th 2 A. hyrcanus fed, the A. maculatus being found dead. On the 27th 4 A. hyrcanus fed. On the 30th 3 A. hyrcanus fed, 1 A. hyrcanus being found dead. On the 31st no A. hyrcanus fed - 2 were found dead. The A. minimus fed a little. On the 1st November the remaining A. hyrcanus and A. minimus were found dead - only the A. maculatus had not taken blood.
A. maculatus. This year the proportion of maculatus larvae examined to the total anopheline larvae collected was less than in former years (33% as compared with 52% in 1932) owing to the areas surveyed including more cultivated and fallow rice fields, swampy tracts and vegetable gardens, places which do not normally function as breeding grounds for this species.
Although the maculatus larvae caught were more numerous than those of any other anopheline, the numbers of adults taken both by day and by night were small in comparison with the catches of other species. Except in the case of the Wo Li Hop collections, those captured were usually not gorged with blood. Malaria infections of the midgut have however been encountered and on two occasions larval filaria were met with in the thorax.
Experiments were made with a frog and with a canary to ascertain if batches of A. maculatus could be induced to feed on them, but on neither occasion did they take blood. Sixteen maculatus were left with a frog for three nights continuously but did not feed on it. Fifteen maculatus were put with a canary for one night but none took blood. In the morning four of the fifteen fed greedily on the arm of an inspector. Another batch of fifteen were left for three nights continuously with a different canary but did not bite. When the bird was removed, an arm was offered for forty minutes but without result. All the anophelines used in these experiments were hatched out in the laboratory, had been fed for a few days prior to the experiments on water and raisins, and had access to the same during the trials.
M 138
(a) INVESTIGATION OF SPECIES AND THEIR LIFE HISTORIES.
Anophelines.
The number and species of the various anopheline larvae examined are given in Table I. Table II gives the number and species of the imagines obtained from pupae collected, and from pupae obtained from the larger larvae.
An experiment was performed in order to obtain an approxi- mate estimate of the number of days which Anophelines might live, if unable to leave a dwelling, and if only blood meals were available. On the 23rd October a batch of Anophelines consist- ing of 4 A.. hyrcanus, 1 A. maculatus and 1 A. minimus which had recently hatched out in the laboratory were transferred to a lamp glass whose ends were covered with mosquito netting. The mosquitoes were allowed access to raisins and damp lint was placed on the top of the netting. At & a.m. on the 24th the lamp glass was applied to an arm and 1 A. hyrcanus fed. The raisins and water were withheld but a blood meal was afterwards
offered daily at 8 a.m. On the 25th 3 A. hyrcanus fed; on the 26th 2 A. hyrcanus fed the A. maculatus being found dead. On the 27th 4 A. hyrcanus fed. On the 30th 3 A, hyrcanus fed. 1 A. hyrcanus being found dead. On the 31st no A. hyrcanus fed -2 were found dead. The A. minimus fed a little. On the 1st November the remaining A. hyrcanus and A. minimus. were found dead-only the A. maculatus had not taken blood.
A. maculatus. This year the proportion of maculatus larvae examined to the total anopheline larvae collected was less than in former years (33% as compared with 52% in 1932) owing to the areas surveyed including more cultivated and fallow rice fields, swampy tracts and vegetable gardens, places which do not normally function as breeding grounds for this species.
Although the maculatus larvae caught were more numerous than those of any other anopheline the numbers of adults taken both by day and by night were small in comparison with the catches of other species. Except in the case of the Wo Li Hop collections those captured were usually not gorged with blood. Malaria infections of the midgut have however been encountered and on two occasions larval filaria were met with in the thorax.
Experiments were made with a frog and with a canary to ascertain if batches of A. maculatus could be induced to feed on them but in neither occasion did they take blood. Sixteen maculatus were left with a frog for three nights continuously but did not feed on it. Fifteen maculatus were put with a canary for one night but none took blood. In the morning four of the fifteen fed greedily on the arm of an inspector. Another batch of fifteen were left for three nights continuously with a different canary but did not bite. When the bird was removed an arm was offered for forty minutes but without result. All the anophe- lines used in these experiments were hatched out in the labora- tory, had been fed for a few days prior to the experiments on water and raisins and had access to the same during the trials.
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