138 NATURAL HISTORY OF INSECTS. 



Genus ICERYA (Signoret). 



Antennae eleven-jointed ; body covered with a cottony mat- 

 ter of several shades of color, and with a secretion of still 

 longer filaments ; skin with rounded spinnerets and 

 Fig. 32i>. w j^ n long, scatterqd hairs; antennae of nearly same 

 width throughout their whole length, and with a 

 long pubescence ; the digitules of the claws are 

 elongated and buttoned, those of the tarsi appear 

 as simple, hairs ; genital apparatus terminating in 

 a tube internally, with a reticulated ring, and with- 

 out hairs at its extremity. Antennae of the larva 

 six-jointed, with a very long pubescence, and with 

 four hairs upon the last joint much longer than 

 the others ; lateral lobes of the extremity of the 

 abdomen with a series of three very long, frequently interlaced 

 bristles. Example The Cottony Cushion-scale (Figs. 295 

 and 325). 



CHAPTER XXI. 



BENEFICIAL INSECTS. 



The greater number of insects feed upon the various parts 

 of plants and are therefore termed ''injurious ;" others feed 

 upon decaying animal or vegetable matter and are called 

 "scavengers;" still others feed upon insects, especially upon 

 those which are injurious to plants, and, because of thus aiding 

 us in getting rid of these pests, are termed "beneficial insects." 

 Some of this latter kind seize their prey with their jaws, some- 

 what in the manner of a cat's catching a mouse, and are hence 

 called u predaceous." To this class belong the Tiger-beetles, 

 which may frequently be seen running over the ground during 

 the hottest part of the day. The one most often met with is 

 the Common Tiger-beetle (Fig. 240), which is of a dull purplish 

 color above, and a bright brassy-green color underneath ; on 

 each wing-case are three irregular whitish spots. Another 

 species which quite closely resembles the foregoing is the Gen-" 



