250 The Orders of Insects 



The Danaina have the anal nervures of the forewing forked at the 

 base, the cells in both wings closed, and the front feet of female 

 thickened. The larv^ are smooth with fleshy processes. They range 

 all over the warmer parts of the world, and far north in America, 

 though not in Europe. 



The Ithomiina: differ from the Danaina; in the slender front feet of 

 their females and the larvae are covered with small elevations. The 

 wings in many genera are almost destitute of scales. The sub-family 

 is confined to tropical America. 



The Acraime are narrow-winged butterflies, of brown and reddish- 

 brown colour with the cells of the wings closed and the anal nervure 

 simple ; the palps are thick and hairy. The larv2 have long branch- 

 ing spines. The Acrxmz occur in tropical America, Africa, India, 

 and Australia. 



The Heliconii/iis are brightly-coloured, narrow-winged butterflies, 

 distinguished from the Acrsins by the palps which are compressed 

 and scaly at the sides, and hairy in front. The larvz have branched 

 spines. These insects are confined to tropical America. 



The Nymphalina: are a very large sub-family of world-wide dis- 

 tribution characterised by the open cells of the wings ; at most a 

 vestigial discocellular nervule is present. The larv^ are spiny or 

 smooth (figs. 88, 89, 139). 



The Morphm,£ are large butterflies with the cells closed in the fore- 

 wings and open in the hind-wings. The larvse are smooth or hairy 

 with the tail-segment forked. This group is confined to tropical 

 America, India, and Indo-Malaya. 



The Brassolims are robust butterflies with the cells closed in both 

 wings, which are usually adorned with large "eye-spots" beneath. 

 These insects, which have larva with a forked tail-segment, are 

 confined to tropical America. 



The Sati^rina have compressed palps with long bristly hairs, the cells 

 closed in all the wings, and the sub-costal nervure greatly thickened 

 (fig. 90). The larvje have a forked tail-segment and are smooth or 

 clothed with short hairs. The sub-family is world-wide in distribution. 



ORDER 14.— DIPTERA. 



Structure. — The Two-winged Flies which make 

 up this order are sharply marked off from all other 

 insects by the reduction of the hind-wings to stalked 

 knobs ("balancers" or halteres), the fore-wings alone 

 being of use for flight ; their mechanism is however 

 so perfect that the motion of Diptera through the 

 air is perhaps more accurate than that of any other 

 insects. The head is usually very convex with large 



