No. 3.] Calcutta Municipal Water. 191 



black; this, however, is no great difference. In our figure, plate XV 

 fig. 5, the insect is shown at a slight angle and gives one a false idea 

 as to the width of the head, it being all but as broad as the thorax. 



Plate xv. Figs. 5, 5 a, 5 b and 5 c show the larvae, pupa, male and 

 female perfect insects all much enlarged. 



In Colombo, Ceylon; a species of Chironomus ) inhabiting the lake 

 in the city, has in the perfect state constituted itself a nuisance. 

 Its life history has been studied and remedies proposed for its de- 

 struction by Mr. E. Ernest Green, Government Entomologist, Ceylon, 

 and Dr. Albert J. Chalmers, M.D., F.R.C.S., who has done excellent 

 work on the mosquito malaria question in West Africa. Their 

 reports on the subject were printed in the Times of Ceylon on 

 August 16th and 28th, 1901, respectively. These reports being 

 highly interesting are reproduced below. 



THE COLOMBO LAKE FLY NUISANCE 

 Report of the Special Government Entomologist. 



My visit to Colombo extended from Tuesday, July 30th, 

 to Friday, August 2nd, during which time I studied the life 

 history of the " Lake Fly " and made the following observa- 

 tions : — 



The insect proves to be a species of Chironomus, one of the 

 aquatic flies, the early stages being passed in the water of the 

 Colombo Lake. 



The eggs of the insect are embedded in irregular masses of jelly, 

 looking like miniature masses of frog-spawn. The ova are arranged 

 in this gelatinous mass in transverse rows, or rather, in one con- 

 tinuous string which traverses the mass, looped transversely from 

 side to side. An average-sized egg-mass may contain over 1,000 

 individual eggs, produced — presumably — by a single fly. I found 

 these egg-masses, in large quantities, attached to floating sticks 

 and rubbish and to the stems of herbage growing in the water at 

 the edge of the lake and on the margins of the small islands. The 

 most favourite situation appeared to be upon floating or partly sub- 

 merged sticks and branches. This is probably due to the fact that 

 such objects afford a firmer support to the fly when ovipositing. 

 The eggs may also be attached to wooden piles or masonry rising 

 out of the water. 



The larvae resulting from these eggs sink to the bottom of the 

 lake and burrow into the oozy mud, forming therefrom rope-like 

 tubes composed of particles of earth and vegetable matter. I found 



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