BIRD-LICE (MALLOPHAGA). 255 



Stone-flies, Termites, &c. The Bird-lice, Mallophaga, all 

 wingless parasites, also belong to this order. 



The N"europtera are grouped in five divisions and eleven 

 families, as follows : — 



1. Trichoptera. — No mandibles in adults. The wings develop 

 internally, becoming evident when the pupal form is attained. 

 Larvse and pupae aquatic. Family Phryganeidce (Caddis-flies). 



2. Neuroptera planipenna. — Adults always mandibulate. 

 Some are aquatic, others terrestrial during the early stages. 

 Development as in Trichoptera. Families Panorpidce (Scorpion- 

 flies), Sialidce (Snake- and Alder-flies), HemerohiidcB (Lace- 

 wings and Ant-lions). 



3. Neuroptera amphibiotica.^ — Wings develop prominently 

 outside the body. Aquatic larvae and pupae. Families Odonata 

 (Dragon-flies), Perlidce (Stone -flies), and EphemeridoB (May- 

 flies). 



4. Pseudo-neuroptera. — "Wings develop as above. No definite 

 pupa. Entirely terrestrial. Families TermitidoB (White Ants), 

 PsocidcB (Book-lice), and EmhiidoB. 



5. Mallophaga. — Wingless and parasitic. 



Bird-lice (Mallophaga). 



Birds are subject to a number of lice : these lice are called 

 Mallophaga, and are included in the order Neuroptera. They 

 are all apterous, and provided with a biting mouth, taking their 

 nourishment from the epidermal products of the skin. The 

 ova are laid on the host; the larvae are like the adult, only 

 paler in colour-^ in fact, metamorphosis is very slight, the 

 young gradually getting darker in colour as they grow older. 

 There is one genus (Trichodectes) (fig. 131) found on mammals, 

 such as the Horse, Ox, and Sheep Louse, &c., and some- 

 times these cause severe pruritus. This genus, as seen in 

 the dog, may serve as a host for one of the Tapeworms that 

 infests the dog. The Bird -lice are often very injurious to 



