1889.] 



THE YOUNG NATURALIST. 



93 



same colour. The meso and meta-thoraces are found to be found to 

 be unusually well developed in the Dragon Flies, which characteristic 

 alone is sufficient to indicate insects accustomed to make full use of 

 their wings. The great length of the abdomen is likewise a familiar 

 feature in these predacious creatures. 



The Ephemeridce comprise another highly interesting group of 

 Neuropterous insects. They may be seen in large numbers in damp 

 marshy grounds or gambolling over the surface of the water wherein 

 they passed the greater part of their existence. The posterior wings 

 in this group are dwindled down to very inconsiderable dimensions, 

 considering the high development they obtain in allied families. 

 Prof. Westwood mentions their entire absence in some species. 

 These insects seem to undergo a double metamorphosis from the pupal 

 to perfect state, throwing off, after a brief and laboured flight of a few 

 feet, a second skin, which envelopes the whole of the body and wings. 



In the Perlidce or Stone Flies, the hind-wings are folded, and all 

 four are greatly reticulated and covered with hair. 



Some species of Myrmelionidce have the hind-wings resembling a long 

 slender shaft, expanded at the tip, but the general character of these 

 members is apparent with a magnifier, but in Asculaphus filipennis, an 

 Indian species, they become mere threads of great length. 



The Termites or White Ants are natives of tropical climes, and are 

 also abundant in the warmer countries of Europe. Both sexes are 

 provided with wings, but the neuters are destitute of them. After 

 pairing, the male and female throw them off at the roots by jerks, 

 having then no further use for organs that would only prove an 

 incumbrance. 



The wings of Hymenopteva are not covered with such an intricate 

 interlacement of nervules as those of the order just considered, but 

 are confined to the possession of the principal branches to which I 

 have already referred. Notwithstanding this, such is their infinite 

 variation, that they have been adopted by entomologists as a ready 

 means of discriminating between obscure species. A well-known 

 feature of the wings of this order is a marginal spot, called the stigma, 

 caused by a peculiar dilatation and apparent interruption of the costal 

 nervure of the anterior wing. This occurs at a point about three-fifths 

 of the distance from the base to the apex. The enclosed trachea is 

 greatly thickened, but pursues its sinuous course without a break. 

 The costal nervure does not always run to the extreme apex of the 

 wing, but, as in most Apidw, stops abruptly half-way between the 

 stigma and anterior angle : it then describes a return curve to the 



