SCALE INSECTS. 269 



Scale Insects (CoccioiB). 



These Hemiptera are peculiar in many respects. The females 

 are mostly apterous apodal degenerate creatures, devoid of 

 antennae, and often lie hidden under a scale-like mass, formed 

 by the excretions of the insect and the cast skins of the larva 

 (exuviae). They have a very long thread-like beak, which is 

 thrust into the bark, leaf, or fruit of the plant, most females 

 being fixed during the whole of their life, after the larval 

 stage is passed. The males (fig. 15.5, i) are winged, having one 

 pair only, the second pair being hook- 

 like processes. The male scale (vi) is 

 quite different from the female scale (v) 

 in form. Some Coccids, such as the 

 Mealy Bugs and Soft Scales, form no 

 scale, and are active in the former, but 

 become sedentary in the latter, but are 

 then covered with a quantity of mealy 

 powder and wool or a hardened skin. °" 



During winter some of our outdoor scales ^'g-,i5,t-fS:rH?r,-.lT* 

 are in the egg state (Mussel Scale) ; the 



ova are minute dust-like bodies found under the scale ; others 

 pass the winter as immature forms (Leeanmm, &c.) In warmer 

 and tropical climates scales breed all the year round, and so they 

 do in hothouses in this country. The young scale-insects are 

 active six-legged larvae (iv), which wander about for a time 

 and then settle down and may form a small scale, gradually 

 increasing in size. If this larva is going to become a female, 

 as it moults it loses its legs, antennae, &c., and usually de- 

 generates into a sedentary apodal creature. But if the larva 

 is going to become a male, it enters a propupal stage, a new 

 set -of legs, &o., being formed, and wings appear as bud-like 

 outgrowths. They are very numerous and destructive in warm 

 climates, where fruit-trees are encrusted with them. Perhaps 

 the most destructive is the San Jose scale (Aspidiotus per- 



