92 OUR INSECT FRIENDS AND FOES 



propelling it through the water, the body of the 

 Corethra larva is destitute of limbs. The head 

 of the nearly full-grown larva presents a most 

 striking and forbidding appearance, the great 

 compound eyes giving the face a very grotesque 

 expression. The antennae are not mere sensory 

 organs as in most insects, but are used very 

 largely in the capture of prey; they project 

 forward and downward like fangs, terminating 

 in four or five long bristles. The mandibles are 

 well developed, and are furnished with four or 

 five long, curved, almost finger-like teeth, which 

 make them look like miniature hands. In the 

 larval stage the Corethra has no spiracles, and 

 but an imperfect tracheal system, which consists 

 mainly of tubes running the whole length of the 

 body ; the tubes dilate in the thorax and again 

 near the end of the abdomen into good sized air- 

 sacs, filled with air, and are of dark colour owing 

 to the presence of pigment cells. The nymph, 

 however, draws in its air supply directly from 

 the atmosphere by means of respiratory trumpets, 

 in a very similar manner to the Gnat nymph, 

 which it also somewhat resembles in appearance. 

 The so-called " Bloodworm " familiar to all 

 anglers, and which abounds almost everywhere 

 in stagnant water, is really the larva of a pretty 

 little gnat-like fly called Chironomous. The 

 pigment which gives the Chironomous larva its 

 characteristic blood-red colour is identical with 

 the haemogoblin of vertebrate animals, and acts 

 in the same way as an oxygen carrier, readily 

 taking up dissolved oxygen, and gradually part- 

 ing with it to the body tissues. With the help 



