LEAVES FROM MY NOTE-BOOK. 143 



hooked to the silken threads with which the cocoon is lined. 

 After the pupal stage comes the question as to how a minute 

 gauzy fly can escape from the rushing water into the air. Through 

 its elaborate respiratory appendages, the pupa draws in sufficient 

 air to inflate its pupal skin ; this at the proper time splits along 

 the back, and a small bubble of air emerges, rises quickly to the 

 surface of the water, and then bursts. When the bubble bursts, 

 out comes the fly. It spreads its hairy legs and runs upon the 

 surface of the water to find some solid support on which it can 

 climb ; and, as soon as its wings are dry, it flies to the trees or 

 bushes overhanging the stream. 



The ascent of the Simulium fly through rushing waters is 

 rendered safe by the hairy covering of the body ; the surface-film 

 clings to the fine hairs, and keeps the air imprisoned and the fly's 

 body dry. In the same way a covering of velvety hairs prevents 

 the Diving Spider, as well as many diving insects, from wetting 

 that part of their bodies which bears the spiracles. 



Few objects in natural history are more enticing to the imagi- 

 nation than the Dragon fly ; its etherial beauty, its gauzy wings, 

 and jewelled body, make it seem hardly a thing of earth. Yet, 

 alas ! further knowledge shows this spirit-like creature to be a 

 merciless carnivore, its mouth filled with the little insects it stores 

 up for eating at leisure. The ugly, sluggish larva of the Dragon 

 fly is armed with one of the most murderous weapons it is possible 

 to conceive. " The policy of the slow Dragon-fly larva is to lie 

 still, in the shady recesses of water-weeds, till its victim comes 

 within easy reach ; then, quick as lightning, it stretches out an 

 arm-like extension of the head, and seizes its prey. The weapon 

 so employed is a peculiar modification of a pair of limbs attached 

 to the head, and called the second pair of maxillae. In insects 

 these appendages form the third pair of jaws, and are formed 

 more or less completely into a labium or under-lip. The labium 

 of the Dragon-fly is carried on a jointed arm, usually much 

 expanded at the end. Side-pieces corresponding to the labial 

 palpi are attached, and there is commonly a pair of spines or 

 claws, which secure the struggling victim. When the larva is at 

 rest the apparatus is folded up, the broad joint being spread over 

 the front of the mouth, while the arm is bent backwards between 



