Mortality among Snails and the Appearance of Blue-bottle Flies

Abstract

THE residential parts of Calcutta are remarkably free, as a rule, from both house-flies (Musca, spp.) and blue-bottles. This is doubtless due to the excellence of the municipal sanitary arrangements, for at Sibpur, a few miles away, blue-bottles (Pycnonoma or Lucilia dux) are not only extremely troublesome in the houses, but are also probably connected with frequent epidemics of enteric, unknown in the better parts of Calcutta. For some years past I have noticed in the compound of the Indian Museum that Pycnonoma from time to time becomes relatively numerous, and on several occasions I have been able to trace the flies to their breeding-ground. This has always been the dead bodies of the snail Achatina fulica, the largest land mollusc in Bengal.