Studies on anopheline mosquitoes in Tokyo : II. Some morphological observations

Abstract

Adult anopheline mosquitoes were collected in houses and stables in the vicinity of the Fujimi pond stated in the lst report. The collection of the mosquitoes was made from time to time during the period from July to September, 1948, and 35 females were obtained in total. Most of them were Anopheles hyrcanus v. sinensis, only one A. koreicus being found among them. These mosquitoes were kept alive, feeding blood meals and sugar solutions, until they oviposit. A batch of eggs laid contained from 60 to 280 (mean : 201) eggs and measurements of 200 eggs gave the dimension of 0.506-0.707mm (mean : 0.585mm) in length and 0.145-0.209mm (mean : 0.187mm) in breadth. These eggs were kept in the dish and the larvae, hatched from them, were bred until-they reached to the 4th stage larvae. The morphological characteristics of the larvae of each stage were examined in detail to find, if any, criterion to distinguish the stages of the larvae. Though hairs or groups of hairs on head, thorax and abdominal segments were examined, none of them was decisive of distingu shing the stages of the larvae except the side hair of the 3rd abdominal segment. The number of branches of this hair was quite characteristic of each stages of the larvae, never overlapping with each other, viz : The first stage : two hairs, single to 3 branches. The second stage : one hair, 4 to 8 branches. The third stage : one hair, 9 to 16 branches. The fourth stage : one hair, 17 to 29 branches. These findings are in accord with those reported by Shibata (1947) who collected larvae from ponds and suggested these characteristics statistically.