262 



Arthropoda. 



2. The Soorp ion -flies (Panorpa), are characterised by the snout-like 

 elongation of the head ; the males by the presence of pincers at the end of the 

 abdomen, which hke the sting of the Scorpion, may be cvirved upwards. Wings 

 small and uniform, body and legs slender. Actively predaceous ; length about 

 10 m/m. The larva (with prolegs) lives in the eai-th, upon decaying matters. 

 P. communis abundant everywhere in the summer. Another f oi-m is the springing, 

 apterous (possessing nidiments of wings), Boreus hiemalis, about 4 m/m. long, 

 which occurs in the imaginal state, from October to Mai-ch, sometimes even on 

 glaciers. Larva, like that of Panorpa. In Great Britain. 



3. Spring-flies or Oaddis-flies (genus, Phryganea and others). 

 Wings hairy or scaly ; the hind wings, which are broader than the fore, are 

 folded beneath the latter ; the veining is less pronounced than in the Ant-lions. 

 The antennse are long, the mouth-parts I'udimentary and functionless. The 

 larvsB are aquatic ; the abdomen is long and cylindrical, bearing thread-like 

 tracheal giUs laterally, and hidden in a tube foi-med of fragments of plants, snail 

 shells, or stones, often very regular in construction ; the particles of which the 

 tube is composed, are held together by a web. When the animal moves about, 

 the head, legs, and thorax protrude from the tube ; it is attached to the tube by 

 means of two hook-like caudal cerci, and often by stout outgrowths of the first 

 abdominal segment. In some forms, the tube is attached to some foreign body, 

 a large stone or the like, and, in all before pupation, it is fastened to some object 

 in the water, and is then closed by a network of thi-eads ; the pupa, like the 

 larva, possesses tracheal gills. 



The small group, Strepsiptera, has been regarded by some authorities as 

 belonging to the Neuroptera ; its systematic position is, however, doubtful. The 

 larvse (genera, Xenos, Stylops, etc.), live in the larvae, and, later, in the imagines of 

 Bees and Was^s, the host undergoing metamorphosis in spite of the presence of 

 the parasite. Before pupating, the strepsipteran larva pushes half-way out 

 of the body of the host between two abdominal rings ; and here the pupa may be 

 found with one end projecting. Sexual dimorphism is well-marked; the male 

 possesses well-developed eyes and legs (without claws), and large hind wings. 



Kg. 220. 1 — 4 Xenos EossU. 5 X. Peckii. 1 Newly -hatched 'larva. 2 Fully grown 

 female larva. 3 Female (imago)- 4 Fully grown male larva. 5 Male (a fore-wing). — 

 1 — 4 after v. Siehold, 5 after Kirby. 



which can be folded up lengthways, whilst the fore wings are quite radimentai-y. 

 The female is maggot-like, without limbs, wings, or eyes ; it does not leave the 

 host, but pushes out a portion of its body, and is there sought out by the male, 

 and fei-tilised. The embryos are developed within the body of the parent, and 

 hatch out as hexapod larvse, which move actively about in the host, and later, 

 bore into its larvse, where they become maggot-like. In the larva, and in the 

 adult female, an anus is wanting. 



