742 



CLASS IV. INSECTA. 



Schizophora and (v) Pupipara. The first two groups have an 

 obtected pupa and the imago emerges through a dorsal slit in the 

 pupa-case. In the case of the Aschiza and Schizophora the 

 pupa-case is formed of the skin of the last larval stage, though 

 this is altered by chitinous deposits and shrinkage, and the 

 imago emerges by a splitting at the anterior end. The last 

 group, Pupipara, consists of certain aberrant flies and is probably 

 not a natural assemblage. 



Group 1. NEMOCERA. 



Antennae slender, at least seven segmented, not ending in a bristle. Palps 

 with four or five segments. They are long, as are usually the legs and body. 

 Fam. 1. Cecidomyiidae. Minute delicate flies with very few wing 

 The Gall -midges form a very extensive and cosmopolitan family. 



nervures. 



Antennae elongated with rings of hairs. 



Ocelli very rarely present. 

 The head is large, the 

 antennae are monili- 

 form with thirteen 

 segments in the female 

 and twenty-four at 

 least in the male. 

 There are eight seg- 

 ments in the cylin- 

 drical abdomen. The 

 larvae are small mag- 

 gots with as many as 

 thirteen postcephalic 

 segments. The ven- 

 tral surface of the first 

 of these segments 

 bears a chitinous pro- 

 cess of debatable 

 function. Many of the 

 larvae burrow in 

 plants and their pres- 

 ence produces galls 

 and other vegetable 

 malformations. Ceci- 

 domyia destructor, the 

 Hessian fly, weakens the stems of Wheat and causes them to bend over, 

 C. tritici attacks the flowers of the same plants. Paedogenesis occurs 

 in Miastor and in Oligarces, the larvae producing young which live on 

 the tissues of their parent and finally leave its body by boring a hole 

 in its skin. 



Fam. 2. Myeetophilidae. More robust than the previous family with 

 more wing nervures and with ocelli. Antennae without whorls of hairs. 

 Legs spiny. This cosmopolitan family includes the flies known as Fungus 

 midges or Fungus-gnats as the larvae live amongst fungi and decaying 

 plants. They are long, fleshy maggots, some of which spin a cocoon before 

 pupating, or make an earthen cell. Many, e.g. Sciara, secrete a mucus, 



FIG. 



474. Cecidomyia tritici (after Wagner), a female 

 with protruded ovipositor ; b larva ; c pupa. 



