GRASSHOPPERS, LOCUSTS, AND DRAGONFLIES. 



569 



and Collembola separately, .many groups besides these are regarded by some 

 authors as forming distinct orders. 



Although the size and importance of the dragonflies indicate them as the 

 true types of the Liunean Netiroptara, yet they have sometimes been united 

 with the Orthoptera under the absurd term Fseudo-neurop- 

 tera. But the dissimilarity of their wings is quite suflBcient Dragonflies 

 to preclude their being classed in the same order as the (Odonata). 

 Orthoptera, \ while if they were, the name Orthoptera would 

 have to be abolished, being of post-Linnean date, and its contents transferred 

 to the Neuroptera. The dragonflies are frequently called Odonata. 



They are generally slender-bodied insects, with long, moderately broad 

 wings, and a large head, the greater part of which, however, is occupied by 

 the two large compound eyes. Their wings are generally 

 colourless, but in some species are very brightly coloured, in Metamorplioses. 

 whole, or in part, with iridescent purple, blue, green, or 

 scarlet. The commonest pattern, where any exists, and which reappears in 

 several distinct families, is a broad purplish-brown band across the middle of 

 both pairs of wings. They are predaceous insects in all their stages. The 

 larva and pupa are brown, and live in fresh water ; the pupaj can be dis- 

 tinguished by their conspicuous wing-cases. When the pupa is matured, it 

 leaves the water, climbing up a reed, or some other convenient support, and 

 then splits down the back, to allow of the emergence of the perfect 

 insect. 



The neuration in some of these insects is often very complicated, the net- 

 work forming many thousands of cells in each wing in some species, while 

 others exhibit comparatively few nervures. They are divided 

 into several families and sub-families, of which we will notice Family 



two or three. In the Libellulidce, the triangular (or more Libellulidos. 

 rarely, quadrilateral) space near the base of the wing, from 

 which several of the principal longitudinal nervures of the wings start, is 

 differently shaped in the fore and hind wings, and the eyes are contiguous, 



but rarely united by 

 a long suture. This 

 family takes in the 

 greater part of the 

 moderate-sized dra- 

 gonflies with rather 

 stout bodies, the com- 

 monest of which, 

 Lihellula depressa 

 (Linn.), which may 

 often be seen flying 

 over water, has trans- 

 parent wings three 

 inches in expanse, and 

 a flattened and rather 

 short and broad body, 

 which is blue in the 

 male, and yelluw in 

 the female. Wu have 

 figured a common South American species of this family, Triihcmis umbrata, 

 (Linn.). The Gomphidce resembles the Libellulidce, but the eyes are distinctly 



Fig. 47.— Dragonily (Trithemis umbrata). Nat. size. 



