194 



ARTHROPODA 



The sheep tick, the horse tick and various bird ticks belong to 

 the sub-order Pupipara. 



Order 17. Siphonaptera. (Fleas.) — The Siphonaptera, or fleas, 

 are wingless, with sucking mouth parts and complete metamorpho- 

 sis. There are about 50 species in the United States. The common 

 cat and dog flea, Ctenocephalus canis, attacks man. The human 

 flea (Pulex irritans) and the chigoe or " chigger " {Sarcopsylla pene- 

 trans) are important enemies of man, the latter burrowing into the 

 skin. This is not the common chigger, which is a mite. (See page 

 201.) 



The rat flea {Laemopsylla cheopus) transmits bubonic plague from 

 rats and ground squirrels to man. Fleas may start out with one 

 animal as a host and transfer to its enemy. 



Order 18. Coleoptera. (Beetles.) — The beetles have four 

 wings, well-developed biting mouth parts, and a complete meta- 

 morphosis. There are over 12,000 species found in America, ex- 

 clusive of Mexico. 



The tiger beetles (Cicindelidae), both in the larval and adult 

 states, are important enemies of insects and crustaceans. The 

 larvae live in holes in the ground. The ground beetles (Carabidae) 

 are extremely important predaceous insects. They destroy the 

 larvae and adults of many injurious leaf-eating insects. The cater- 

 pillar hunter (Calosoma scrutator) is an important enemy of the 

 hairy " tent-caterpillar." Other forms attack cut-worms and 

 canker worms. A few species feed on young grains, but the majority 

 of the Carabidae are beneficial. The carnivorous water beetles 

 (Dytiscidae), a.re important enemies of mosquitoes and other injurious 

 insects. The larva, the ferocious " water-tiger " traps air under the 

 hairs of its tergum and is able to remain under water for some time. 

 Large " tigers " reach a length of three inches. The water scavengers 

 (Hydrophilidae) are large forms living under the surface of water 

 during the day, but flying to lights at night. They are black and 

 over an inch in length. The whirligig beetles (Gyrinidae) are small 

 aquatic forms not more than ^ of an inch long. Children some- 

 times call them " money-bugs." The lady bugs (Coccinellidae) or 

 " lady-bird beetles " are predaceous in the larval as well as the 

 adult condition. They are important agents in the control of plant 

 lice and scale insects. The genus Epilachne is herbivorous. 



The carpet beetle (Anthrenus scrophulariae) attacks rugs and 

 clothing, including feathers. The club-horned beetles (Clavicornia) 



