A monograph of the Anopheles mosquitoes of India / by S.P. James and W. Glen Liston.

  • Sydney Price James
Date:
1904
Catalogue details

Licence: In copyright

Credit: A monograph of the Anopheles mosquitoes of India / by S.P. James and W. Glen Liston. Source: Wellcome Collection.

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    Swarming. regard to these insects. A rossi ediibited the phenomenon in the greatest degree. In July, larvae of this species were practically never seen, and even for some time after the onset of the rains its larva3 were never found in the numerous pools then formed. By the third week after the commencement of the rains its larvae were present in many pools, and by the sixth week they were very abundant. By the middle of September larvae of this species were present in enormous numbers in all the pools round the bazaars and in most of the pools throughout the whole country-side. The adult insects showed a corresponding increase, and though found with the greatest difficulty before the onset of the rains they were present in immense numbers in every bazaar and village in the neighbour- hood a few weeks later. In spite of the fact that a reduction in breeding places occurred at the end of September, they remained in large numbers until the end of October and then rapidly disappeared. THE CHARACTERISTIC POSITION ASSUMED BY ANOPHELES WHEN RESTING ON ANY SURFACE. Many mosquitoes can be immediately recognised as anopheles” by the characteristic position which they assume when resting on a wall or roof From a short distance they look somewhat like thorns projecting from the surface (PL III, 5, 6). The reason why anopheles ” rest in such a characteristic position would seem to be that the proboscis, head, thorax and abdomen of a mosquito of this kind lie in one straight line, so that when the proboscis is directed towards any surface, the abdomen is directed away from that surface. The angle formed between an anopheles and the wall on which it is resting differs with different species, and with practice it is often possible to name a species by merely observing the angle which it forms with the wall. A. rossi, for example, rests at an angle of about 45° with the wall, while A fuligmosus forms very nearly a right angle with it. Cuticijacies, aitkeni and cidiciformis lie almost, if not quite, parallel to the surface on which they are resting, and Annett and Dutton have shown that in a state of hibernation maculipennis does not form an angle with the surface upon which it is resting, but lies with its whole body nearly touching the wall. It will be noticed, however, that the proboscis, head, and body of an “ anopheles,” in whatever position it is resting, are always 56]