SCALE INSECTS. 



insect itself ; others are covered in loose white material 

 like cotton wool which completely envelopes them and 

 gives them their name, mealy bugs. In some the 

 covering takes the form of thick opaque wax, arranged 

 in more or less regular plates. Another large division 

 has no special covering but the skin of the upper 

 surface is thickened. In nearly all species the size 

 is not more than one-eighth of an inch, the insect 

 being flattened and closely attached to the plant. No 

 definite characters can be given by which to distin- 

 guish these insects from many others which resemble 

 them. 



Life History. The female produces very large 

 numbers of eggs, which may hatch at once or remain 

 dormant for a long period. As a rule these eggs are 

 produced slowly and accumulate under the body of 

 the insect or in a special egg case attached to her 

 body. The number of eggs is generally some hun- 

 dreds, often thousands. The young that emerges is a 

 small insect, flattened, with three pairs of legs hidden 

 under the body, a long suctorial beak, and minute eyes. 

 The young walk actively and may go for some distance 

 in search of a fresh food-plant. Eventually each settles 

 down, buries its beak in the tissues of the plant and 

 feeds upon the juices. When grown larger, the skin 

 is shed and the insect often becomes a degraded legless 

 creature hidden under its protective covering. 

 The females moult once 



FIG. 291. 



The Black Shield 

 Scale. 



more and are then mature. 

 Most are incapable of 

 movement after the 

 first moult, though the 

 mealy bugs in particular 

 remain active throughout 

 life. 



The male undergoes 

 two further moults and 

 after passing through a 

 period of rest, emerges as 

 a tiny two-winged fly, 

 so small as to escape 



FIG. 292. 

 The Black Shield Scale. (Magnified five times.) 



