276 



Arthropoda. 



the thorax by a constriction. The 1 a r v se are invariably 

 maggots, i.e., the thoracic appendages are absent. Some, however, 

 still possess a hard chitinised head furnished with eyes, antennae, and 

 mouth-parts. In others on the contrary, the head is not well 

 marked, eyes are absent, the antennee absent or very degenerate, the 

 mouth-parts represented by a pair of darkly-coloured chitinous hooks 

 (mandibles ?) . The larvae live in water, in decaying substances, in or 

 upon plants, or as parasites. In those Diptera whose larvae have well 

 developed heads, the pupae are like those of the Lepidoptera, the 

 appendages lying close to the body ; in those with " headless " grubs 

 the pupEB remain within the last hardened larval skin (coarctate 

 pupae) . 



1. Midges (Nemocera) are usually slender with long antennee, whicli 

 in the males are often furnished with long hairs. The wings are narrow, the legs 

 long and thin. To mention a few forms: G-nats (Culex) antennse of fourteen 

 joints, with long hairs in the male ; maxillary palps in the male longer than the 

 proboscis ; the females alone possess mandibles, and stab and suck blood : the 

 larvae are aquatic ; they have only two stigmata, situated on a terminal process 

 (respiratory tube) ; the pupa is motile, and has two upright respiratory tubes at 

 the front end of the body ; both larvae and pupae usually hang suspended by these 

 respiratory tubes from the surface of the water. The Daddy-long-legs or 



Crane-flies {Tipida) axe 

 J large Midges, the larvae of 



which live in meadows, or 

 in rotten wood. The Gall- 

 flies {Cecidomyia, etc.) are 

 very small delicate forms, 

 the larvae of which, hke the 

 G3mipid8e, frequently live in 

 galls (one of these for in- 

 stance, C. fagi, lives in the 

 well-known pointed gall of 

 beech leaves) ; many species, 

 however, do not form galls, 

 but the larvae are foimd in 

 living or dead plants. In 

 some species of this group, 

 paedogenesis is known to 

 occur (see p. 246). The 

 Sand- fly (Simulia), a 

 small fly-hke Midge, the females of which, like Cidex, are blood suckers ; several 

 of the notorious "Mosquitos" of warm countries are species of this genus; 

 others. Black-flies, e.g., 8. eolwmbactensis, of Hungary, are sometimes, when 

 they occur in large numbers, a teiTible plague to cattle, since they sting them in 

 thin-skinned places, and the result of the wound is inflammation, fever, or even 

 death. The larvae of this genus are aquatic. 



2. Gad-flies (Tabanidse) ; the antenna is said to be three- jointed, but 

 the last joint is constricted, and therefore consists of more than three joints. 

 The head is short and broad, with very large eyes ; the mandibles are only present 

 in the female ; the abdomen is flattened ; the larvae are cylindrical, living in the 

 earth. The females suck blood from Mammalia, and are, for instance, great 

 plagues to Horses in summer. 



Pig. 224. Culex. a larva (head downwards), b pupa, 

 c perfect insect. — ^After Taschenberg. 



