17 



together called 

 Phthiraptera 



What insects are^ and how they are classified 



and these are called just 'psocids'. The winged forms, usually associated 

 with the bark of dead trees, are known as 'barklice'. 



16. Zoraptera (North America 2; world 19) 



These are rare, pale coloured and tiny insects, found largely in tropical 

 climates. In North America, at least one species ranges as far north as 

 central Ohio and is found living in the warmth of rotting sawdust piles. 



. Mallophaga (North America 320; world 2600) 

 Bird lice: 'chewing lice' (Fig. 8). 



18. Anoplura (North America 65; world 250) 



Sucking lice. 



These two groups of lice are conveniently bracketed together, because 

 of their similar habits. They live entirely as external parasites: Mal- 

 lophaga mainly on birds, occasionally on mammals; Anoplura entirely 

 on mammals. Mallophaga have chewing mouthparts, and feed mainly on 

 fragments of feathers, skin, or other organic debris. Anoplura have sucking 

 mouthparts, and actively draw blood from the host animal. The Human 

 Louse belongs to the Anoplura. 



19. Thysanoptera (North America 625; world 3000) 



Thrips. The name Thysanoptera describes the peculiar wings, which 

 are narrow and fringed, like a tassel, though many Thysanoptera are 

 wingless. These tiny insects, often black, can be seen on flower-heads, 

 where they suck the sap. They feed also on other parts of the plant, and 

 several species are recognised as pests: e.g. the Pear Thrips. Some thrips 

 are carnivorous on other insects. 



20. Hemiptera (North America 8750; world 55,000) 



Bugs. Though the word 'bug' is used loosely for any insect, and in the 

 narrow sense for the Bed Bug {Cimex lectularius), to the entomologist a 

 bug may be any member of the Order Hemiptera. These insects have 

 sucking mouthparts (Figs. 11 and 25d), and are divided into Heteroptera 

 and Homoptera. Heteroptera have the fore-wings divided into two, the 

 more basal part being harder, like the fore-wing of a beetle, while the tip 

 remains thin and membranous; Homoptera have the fore-wings uniformly 

 thin. In some books you will find thesQ two groups treated as different 

 Orders. 



Heteroptera (Figs. 10-12) can further be conveniently divided into 

 land-bugs and water-bugs. Land-bugs include species like the Cotton- 

 Stainer, which go from one plant to another sucking the juices, and in the 

 process may carry the organisms of many serious diseases of crops (see 

 Chapter VIII). Some families consist entirely of carnivorous bugs, which 

 feed upon the plant-living insects in the same way that carnivorous 

 mammals feed on herbivorous ones. Some may suck the blood of birds, 

 mammals or man, and live in the nests, lairs or houses of their hosts : e.g. 



15 



