ON THE HABITS OF THE MARINE MOSQUITO 
{A CAR TOMYIA ZAMMITII, Theobald) 
BY 
Surgeon E. H. ROSS, R.N. 
Being a communication received by the Entomological Department of the 
Liverpool School of Tropical Medicine. 
BY my brother's advice, I am sending you some mosquitoes and a fly, with which 
we 1 have been working for some time past, thinking that, perhaps, they are 
concerned in the spread of Malta fever. They will be conveyed to you by 
my colleague, Levick, who is on his way home. The mosquitoes are Acartomyia 
zammitii, Theobald. Most of them were caught in the pupal stage, and hatched out 
into captivity. These pupae were found in the salt pans and pools on the rocks of 
the sea-shore at Malta ; I also append a photograph of some of the typical pools. 
These pools are found all round the island, but the mosquitoes only in those within 
two miles of houses ; on one occasion, however, at Marmarice, Levick found them 
in a sea-water pond, which was used for washing cattle, far away from human 
habitation. Their eggs are laid on the surface of these pools, not on the water itself, 
but always on floating debris, such as floating sea-weed, froth bubbles, straw, etc. If 
the female mosquito has to lay her eggs on the surface of salt water which contains 
no floating particles of this kind, she almost invariably drowns after having laid about 
thirty eggs; but if she can stand on floating sea-weed she again leaves the pool in 
search of food. The larval and pupal stages can only be passed in concentrated 
sea- water, thus : — 
Mediterranean sea-water (summer), twenty-eight grammes per litre salt. 
Acartomyia can only live in water containing from forty-eight to eighty-seven 
grammes per litre of salt. 
As soon as salt begins to be formed on the surface of the pool, the larvae and 
pupae move on to another part of the pool, which is often most extensive. These pools 
may be very deep, but, in common with all the sea-water pools on the shore of the 
Mediterranean, never contain fish or shrimps. When a thin layer of salt forms on 
the whole surface of the pool, the larvae die. 
Daylight, apparently, is not absolutely necessary for the maturation of the 
larvae, for I have found them in cesspools under the houses at Port Said, these 
cesspools containing a large percentage of salt ; but, experimentally, the larval stages 
are much prolonged when daylight is completely excluded. 
i This refers to Surgeon Levick, R.N., Surgeon Ross's collaborator in this work. 
