i8o ARTHROPODA 



Order 8. Thysanoptera. — The thrips are minor pests of wheat, 

 onions, citrus fruits and grasses. Their feet are clawless with blad- 

 ders adapted for clinging to leaves. They have four narrow mem- 

 branous wings, fringed with long hairs. 



Order 9. Euplexoptera. — The earwigs feed on fruit and flowers, 

 but are of no economic significance in America, where they are 

 rare. The mother remains to guard her eggs for a time. 



Order 10. Orthoptera. — The cockroaches, Blattidae, are noc- 

 turnal insects frequenting water pipes and attacking food stuffs. 

 There are four species in the U. S., the common " croton bug " being 

 the form most frequently found. They eat the " silver-fish," bed- 

 bugs and each other. 



The praying mantis, Mantidae, has its front legs peculiarly 

 adapted for seizing and holding its prey. Its peculiar attitude when 

 lying in wait for its food gives it the name " praying." 



The walking sticks, Phasmidae, resemble their background so 

 perfectly that it is exceedingly difficult to locate them at times. 

 They feed on the leaves of trees, usually the oak. 



Locusts or short-horned grasshoppers, Acrididae, have extremely 

 short antennae and well-developed leaping legs. They are impor- 

 tant enemies of plant life and, when they migrate in hordes, seem to 

 devour almost everything. Locusts were eaten in the Orient and 

 are still prized by some savages. (Figure 83.) 



The Tettigoniidae {Locustidae) include the meadow grasshoppers 

 and the katydids. The katydids are large green insects feeding on 

 leaves and tender shoots, but occasionally devouring other insects. 

 'Y\\t females are silent. Certain yellowish brown, wingless forms, 

 living in cellars and caves, are called " cave crickets." 



The Gryllidae have their wings flat on the body and are usually 

 stout-bodied. Many are wingless. The true crickets (house 

 crickets) are black forms, feeding on plants for the most part. 

 The eggs are laid in the ground in the fall and hatch in the summer. 

 The tree crickets are slender and light in color. The " snowy tree 

 cricket " injures grape vines and berry plants. The female guards 

 her eggs. The mole cricket has its front tibiae broadened for bur- 

 rowing. It is an important enemy of growing plants, particularly 

 the potato. 



Type of the Order — Lubber Grasshopper — Rhomaleum Microp- 

 ierum. Anatomy. — The grasshopper is divided into three distinct 

 regions: The head, the thorax with three segments, and the abdo- 



