THE CHITRONOMIDA;, 175 
deposited. These eggs are in the form of long threads of a gelatinous 
nature, in which the ova are embedded in a row. Fig. 38. They are 
usually placed at the side of some weed or twig in the water in nature ; 
in confinement, at the side of the bell-glass or whatever they are con- 
tained in. The pupa on depositing a large number of eggs generally 
ates, and here again we observe a difference to Cecidomyia, where the 
maggots eventually turn to perfect flies. Occasionally the pupz do 
develop, but during the summer this is only exceptional. When 
the autumn approaches the flies always hatch, and after copulation 
deposit fecundated ova in the water and die at once, Grumm 
notices a curious point in this; he says that if the ova are taken 
from an unfecundated fly they develop just the same during the 
autumn, only development is of longer duration. 
Pupe of Chironomt, 
In many respects the pupe of these midges resemble those of 
gnats. They are naked, no puparium or case of any kind being 
présent. They remain at the bottom of the water until near the 
time for the emergence of the perfect insect, when by various move- 
ments they approach the surface. The power of swimming seems 
to be present in all the aquatic forms. ‘Two things are necessary for 
Fic. 39.—Pupa of Chironomus plumosus, 
the extrication of the imago, first, that the thorax, which is always 
placed upwards, should be slightly above the surface of the water ; 
and, secondly, that the chrysalis is level with the surface. The 
imago escapes by the splitting of the upper region of the thorax, 
which has a curious power of repellingjwater. The insect on coming 
out of the orifice formed in the thorax, places its legs on the water, 
and by degrees draws itself completely out of its shell, the case 
forming a boat, much in the same way as seen in the gnat. Oneach 
side of the thorax is a bunch of hairs (five in C. plumosus), which 
form a star when expanded; the anus is also provided with a fan- 
