THE HIBERNATION OF ENGLISH MOSQUITOES 
BY 
H. E. ANNETT, M.D., and J. EVERETT DUTTON, M.B. 
In the British Medical Journal of April 27, 1901, Dr. M. J. Wright records 
some interesting experiments concerning the resistance of mosquito larvae to cold. 
It is truly a remarkable feature that larvae, both Culex and Anopheles, are able to 
withstand a temperature of about 4 0 C. for a period of two weeks. 
Early in December last Mr. T. V. Theobald, of Wye, Kent, sent a number 
of Anopheles larvae to Major Ross, which have been kept continuously in a greenhouse 
at a temperature of from 15 0 C. to 32° C, and, although they are often seen feeding 
on the green protococcal growth supplied, they show apparently very little increase 
in size, and none have as yet changed f into pupae. 
Dr. Wright infers from his observations that the larval form is that in which 
' hibernation' takes place ; never having found adult mosquitoes during the winter 
months. Here his results differ most markedly from ours, which we wish now to 
record in a short preliminary account. It may be mentioned that throughout the 
winter session a supply of Culex adults has been obtainable for class purposes at 
this School. 
On February 17, during a period of very cold weather, four Anopheles were 
caught at a farm some thirteen miles from Liverpool, in North Cheshire. A large 
number of Culex (four species) were also captured here. The Anopheles were 
identified by Mr. T. V. Theobald as A. maculipennis. The mosquitoes were found 
in the following situations : cellar, dairy, cheese room, pantries, lumber rooms, and 
in some disused bedrooms at the top of the house ; also in the wash-house and whey 
tank house abutting on to the house, and in the coach-house, tool sheds, and privies 
at some distance away. No mosquitoes could be found in the stables, cowsheds, 
pigsties, haylofts, henpens. Many of the farm houses of this district of Cheshire are 
old, and have no damp-proof courses. In the disused cellars the walls and the beams 
supporting the ground floor were soaking with moisture, and small ferns grew in the 
crevices of the tiled floor, and patches of moss and mould on the surface of the 
walls. Here thousands of mosquitoes, chiefly Culex, blackened the walls and rafters. 
In the dairies they were found on the damp areas, resting on and in the crevices of 
the plaster ; very few were seen on the drier parts. Similarly in the other places, 
on the damp portions, many mosquitoes were observed, especially behind boxes, 
slates, boards, barrels, and other articles resting against the wall. 
* The greater part of this article appeared in the British Medical "Journal, April 27, p. 1013, 1901. 
f April 16, 1 90 1, 
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