262 HEMIPTEKA-HOMOPTEEA. 



Many of this order are extremely injurious, such as the Aphides 

 or Plant-lice, many of the " Bugs " [Hete)'optei-a) and Scale 

 insects (Corridw), Snow-flies {Aleyrodidm) and Leaf -hoppers 

 {TijpMocyhidce). Many of the Capsi'hf (Land Bugs) also attack 

 fruit. There are generally considered to be three groups of 

 Hemiptera, as follows : — 



L Howo/ttera (fig. 151), wings always clear and membranous 

 when present, and the rostrum attached to frontal 

 region of head = ApMdidic, Coecidw, FsyUida, &c. 



2. Heteroptera (fig. 159), wings half leathery at the base, 



membranous at the tips, and the rostrum springs from 

 beneath the head = the Bugs {Reduviidcs, Lygceidn', 

 CapsidiB, Cimicidii'., &c.) 



3. Anoplura, which are all devoid of wings and parasitic 



= Pediculid(i' or Lice. 



The Homoptera contain the most injurious species of this 

 order. They are exemplified by the Plant-lice (Aphididw), 

 the Scale insects (Con-idn-), the Snow-flies (Aleyrodidip), and 

 the Suckers (PsylUdir.) 



Plant-lice (Aphididje). 



Plant-lice are amongst the worst enemies the farmer, fruit- 

 grower, and gardener have to contend with. They live entirely 

 upon the sap of plants, which they draw from the leaves, 

 blossom, stem, and roots. The structure of an Aphis is simple. 

 The body is usually plump, and has usually two tubes called 

 "honey-tubes" or "cornicles" on the back towards the tail. 

 Out of these is passed a gummy liquid, the " honey dew,'' 

 which falls upon the leaves of the infested plants and blocks 

 up their stomata. Aphides have a mealy or waxy substance 

 on the skin which repels water. Winged and wingless females 

 occur, the males being also often winged. Parthenogenetic 

 reproduction takes place ; both oviparous and viviparous females 



