CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 279 



live within the body until full grown. Tachina flies resemble house- 

 flies but areusually more bristly and hairy. The bristles of the antennae 

 are entirely bare. They are frequently found about flowers and rank 

 vegetation. Besides caterpillars, such as army-worms and cutworms, 

 locusts, leaf-eating beetles and other injurious forms are kept under 

 control by tachina flies. 



HIPPOBOSCID^ (SHEEP TICKS) 



Sheep Ticks {Melophagus ovinus Linn.) are wingless, brownish, 

 flattened blood-sucking insects belonging to the sub-order Pupipara. 

 They are often very injurious to lambs in spring after shearing time. 

 Sheep should, therefore, be dipped twice after shearing in some good 

 "dip," of which several kinds are on the market. (See Farmers' Bull. 

 798, U. S. Dep. Agr.) 



Life-history. — Each female produces 5 to 8 nearly full grown larvse 

 which become brown puparia in about 12 hours. Eggs are not pro- 

 duced. The adult tick emerges in 19-24 days after the deposition of the 

 pupa, and reaches sexual maturity 3 or 4 days later. In 8 to 10 days 

 after fertilization the female deposits the larva. 



ORDER SIPHONAPTERA (FLEAS) 



Pulicidae (Fleas). — (Consult Farmers' Bull. 897, U. S. Dep. Ag.) 

 Two species of fleas are found infesting houses: the Human Flea 

 (Pulex irritans) most commonly found on the Pacific Coast, the Cat 

 and Dog Flea {Pulex serraticeps) in the eastern part of the continent. 

 Fleas are most numerous in sandy regions and in rainy seasons. 



Human Flea {Pulex irritans Linn.). — Secretes itself in bedding 

 and clothing, and attacks its human victims at night. 



Adult. — Body compressed; wingless; legs long and stout; tarsi 

 5-jointed, and mouth-parts adapted for sucking; antennae small, eyes 

 simple. 



Eggs. — ^Laid in dust or lint under carpets and other out-of-the-way 

 places, whitish and ovoid; in summer hatching in 4 to 6 days. Each 

 female lays 8 to 12 eggs. 



Larva. — ^Lives and feeds in dust or htter; slender, worm-like, footless, 

 sparsely haired; full grown in summer in about 11 days, but may be 

 prolonged to several months. 



