Thrips. Cockroaches. Locusts. 125 



ORDER IV. Thysanoptera, or fringe -winged in- 

 sects, including a not uncommon little fly, named 

 Thrips. whose contact with the face in warm weather is 

 often a source of considerable itching from the titilla- 

 tion caused by its plumose wings and bristled body. 

 One species of this order by piercing the immature wheat 

 grain with its bristle-like mandibles causes the seed to 

 shrivel, and occasionally destroys even the corn stalks. 



ORDER V. Orthoptera, straight-winged insects, 

 includes cockroaches, grasshoppers and locusts. 

 These have four wings, of which the often parchment- 

 like front pair are the smaller ; the second pair are 

 usually large, and when at rest are folded like a fan. 

 The mouth is masticatory and both pairs of maxillae 

 are free. Some of the tropical forms of this order 

 are wingless and assume extraordinary forms, the 

 walking leaves, mantis, and w r alking stick (Bacterium} 

 sometimes resembling dry twigs or bits of branches. 

 In the common cockroach (Periplaneta orientalis] 

 which is a native of the East, the legs are fitted for 

 running and have spiny tibiae, the head is over- 

 lapped by the front segments of the thorax and 

 bears long antennae, and the parts of the mouth are 

 distinct (figs. 64, 65). The wings are very small, 

 especially in the females. The Drummer Cockroach 

 of the West Indies adds to its other disagreeable 

 qualities that of making a knocking noise, which is 

 sometimes sufficiently loud to keep awake the inha- 

 bitants of houses infected with these insects. Troctes 

 pulsatorius, a minute insect found in books, old pic- 

 .tures, &c., also produces a sound which has earned 

 for it the name ' death-watch ' or * death-tick.' 



