192 Indian Museum Notes. [Vol. V. 



the whole surface of the mud, near the margins of the lake, com- 

 pletely covered with a tangled mass of these tubules each contain- 

 ing a small vermiform larva of Chironomus. It would be impossible 

 to estimate the number of larvae living at one time in the lakes But 

 from about three cubic inches of the mud, I extracted more than 

 200 larvae. The fully grown larva is about fths of an inch long 

 and of a bright red colour. It is worm-like in appearance, but has 

 some short appendages at both the anterior and posterior extremi- 

 ties. Some of the latter act as gills, permitting oxygenation of the 

 blood while the insect remains submerged. The larva feeds upon 

 decaying organic matter and completes this stage of its existence in 

 the mud. 



The pupal stage is also passed in the same situation until imme- 

 diately before the emergence of the fly, when air forms inside the 

 pupa, causing it to rise to the surface. The pupa is elongate and 

 narrow, about fths of an inch in length, tapering behind and some- 

 what swollen in front. At the anterior extremity is a thick tuft of 

 respiratory filaments performing the office of gills. Just before 

 emergence the pupa rises to the surface of the water, the skin 

 splits, and the fly is liberated. 



The adult fly is a small gnat-like insect of about the size of a 

 common mosquito but of a rather more slender build. It may be dis- 

 tinguished from the mosquito by the absence of prominent beak-like 

 mouth-parts. The species in question is of a dull brownish colour, 

 the thorax longitudinally and the abdomen transversely banded with 

 grey. The wings are transparent and marked with a few brownish 

 specks. The sexes may be distinguished by the presence in the 

 male insect of a pair of densely plumose antennas, while those of the 

 female are small and inconspicuous. The body of the male is 

 slender and measures a little less* than \ inch. The female is stouter, 

 but scarcely more than £th of an inch in length. 



I was unable, during my short visit, to determine the exact time 

 at which the emergence of the flies takes place. I watched the lake 

 carefully from 4 P.M. till 7 P.M. but, though a few individual flies 

 were seen leaving the water, no general ascent of pupas and libera- 

 tion of flies was observed. At about 6 p.m. I saw myriads of the 

 flies resting in the grass and rank herbage on Dhobies' Island. It is 

 possible that they may be hatched out durin* the night or in the 

 early hour of the morning, and that they rest during the day, pre- 

 paratory to their evening flight. The flies were, also observed, com- 

 paratively early in the afternoon, resting on the whitewashed walls 

 of buildings near the lake, and sheltering amongst the plants in the 



