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A NET=BUILDING CHIRONOMUS LARVA. 
A. T. MUNDY. 
In the summer of 1904, Prof. Miall and Mr. Taylor discovered 
a tube-building larva of special interest on account of its strange 
habits. The fly was hatched out, and has been identified as 
Chironomus pusio. The larve were found in great abundance 
at Touthech, Windermere. In 1905 I found that the same 
insect was quite common in some of the South Devon streams 
on the borders of Dartmoor. Inthe Yealm, which is only a few 
minutes’ walk from my home, they are very plentiful, and so I 
have had exceptional facilities for studying their anatomy and 
life history. At first I had the greatest difficulty in keeping them 
alive and active, for they delight in the swiftest running water, 
while I had to keep them in dishes of still water. However, 
this difficulty was finally overcome by using a clock-work 
arrangement, which set in motion a revolving paddle, thus 
stirring the water round and round. And so by this means [ 
have been able during the last two years to study their habits 
and metamorphoses very closely. 
Some of the Chzronomids make free cases just as do the 
caddisworms (Zrichopiera). Reaumur (1743) was the first 
naturalist to describe one of these ; Lyonet described another 
in 1832, which built a gelatinous case. This larva has been 
quite recently found in England. Dr. Lauterborn has now 
added three more to the number of case-builders. One larva 
makes a brown opaque case, rather flat with rounded ends, 
opening by a slit, thus resembling in a remarkable degree 
those old-fashioned spectacle cases which open at either end by 
gentle squeezing. The second makes a straight reed-like case 
covered with scales; the posterior end is closed by a tough 
membrane with a central pore. And the third makes a case 
somewhat the shape of a cigar. None of these cases are more 
than a few millimetres in length, and I am not aware that any 
of them have been as yet found in England, but that is probably 
only on account of their smallness. On the other hand the 
tube-building larvae, among which we place our Chironomus, 
are found in great variety in all parts of England. Some make 
simple mud tubes buried in slime; others build tubes three or 
four inches long rising perpendicularly from the bottom of 
stagnant pools ; while still another group constructs elaborate 
nets, supported by a strong framework of arms, to be used for 
catching food, 
1907 Noyember 1. 
