BIRD-LICE (MALLOFHAGA). 255 



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

 wingless parasites, also belong to this order. 



The Neuroptera 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. 

 LarviE and pupss aquatic. Family Phryganeidai (Caddis-fiies). 



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 pupse. Families Odonata 

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

 flies). 



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

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

 Psoeidte (Book-lice), and Embiidm. 



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 larvas 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 



