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.

    80/238 (page 58)
    other characteristics of larvce and eggs. 3. The resistance of larvcB to drying.—Dr. Christophers also found that larvae could remain alive on soft mud even after exposure to the sun for several hours. If the mud had so far dried as to lose its glistening surface the larvm were found to be dead. 4. The duration of the larval stage.—Dr. Liston found that, under suitable conditions, anopheles ” larvae became pupa^. in about a week, but that with an unsuitable or deficient food-supply they re- mained as larvae for more than a month. At Mian Mir in Septem- ber (the most favourable month), Dr. Christophers found that A. rossi did not pupate until the twelfth day after the eggs were laid. No difference was noted in the case of shallow or deep pools, although the temperature of the water in the shallow pools was high, viz,, 96° F. to 102° F., while that of the deep pools was only 90° F. or less. The adult insects emerged two days after pupation, so that fourteen days {two in the egg form, ten in the larval form and two in the pupal form) would appear to be about the minimum time required for the development of rossi from the egg to the adult stage. The least time in which culicifacies developed from the egg to the adult stage was thirteen days. The same observer remarked that “ anopheles ” were slower to develop than any other kind of mosquito, taking three days longer than (kdex and four days longer than Stegomyice. In the winter months the development of larvae may be almost indefinitely delayed, and, as already mentioned, the larvae of some species may remain without developing into pupae throughout the whole winter (hibernation of larvae). Whether this is due to the temperature of the water being lower, or to a difference in food- supply, is not known, but the experiments of Dr. Christophers recorded above would seem to show that the temperature of the water has little or no effect. There is also a great difference between different species in this respect, for in the Punjab while the larvae of culicifacies remain in a hibernating condition throughout the winter, those of fidiginosus develop into pupte and adults even in the coldest months. 58]