EXOPTERYGOTA 



423 



Order MALLOPHAGA (Biting lice) 



These insects are ectoparasites of birds (less frequently of mammals). 

 Their reduced eyes, flattened form and tarsal claws are features corre- 

 lated with this mode of life. Unlike the Anoplura they have no 

 piercing mechanism and devour with biting mouth parts small 

 particles of feathers, hair, or other cuticular matter. 



The common hen louse, Menopon pallidum (Fig. 313), maybe taken 

 as an example. The head is semicircular in form and articulates with 

 a prothorax which is freely movable on the rest of the body, a tagma 

 formed by the fusion of the meso- and metathorax with the ab- 



md. 



Fig. 313. Fig. 314. 



Fig. 313. Hen louse, Menopon pallidum. Dorsal view, showing biting 

 mandibles by transparency, an. antenna; md. mandible; mxp. maxillary 

 palp; pth. prothorax; msth. mesothorax; mtth. metathorax. 



Fig. 314. Body louse, Pediculiis humanus. After Imms. 



domen. The mouth is placed ventrally on the head and surrounded 

 by biting mandibles and less prominent ist and 2nd maxillae. 



Eggs are laid separately on feathers or hairs and the life cycle is 

 completed in about a month — the young instars resembling the adult 

 in form and habit. 



The various families of biting lice are strictly confined to particular 

 groups of birds, indicating that evolution of the parasites has pro- 

 ceeded concurrently with that of their bird hosts. 



