11 



Scale insects are those which secrete and cover themselves with a 

 waxy or horny shield or scale that protects or hides them from view. 

 Soft scales are so called because the surface covering is yielding in 

 texture and forms part of the real insect: there is no separation 

 between scale and insect, and any injury to the scale is an injury to the 

 insect itself. Armored scales have the shield-like covering separated 

 from the creature that produces it; the latter lies free beneath its 

 shelter and it is quite possible to lift the scale from its attachment 



■■■;/-'<i^ 



u:' K 





Big. 5. 



The formaUon of a scale: o, the larva with its month filaments eitended ; ft, the larva has Bet, 



begun to feed, is becoming more rounded and waxy filaments are exuding ftom the 



sur&ce ; c, the Insect has become circular and the waxy filaments cover It 



completely; d, the filaments have run together and form the 



first scale. From Howard, V. S. Dept. Agl. 



without disturbing the insect. It results, from this that armored scale 

 insects are difficult to reach with insecticides, because they are pro- 

 tected from all but the most corrosive and penetrating materials. 

 Scales differ in thickness and some are much more easily, pierced than 

 others. There is also a great difference in their life history, and no 

 one method will answer for the destruction of all. They agree in 

 having a minute, sis-footed active larva, which crawls about for a 

 few hours— sometimes a day or two— and then inserts the long, slen- 

 der lancets that serve it for mouth-parts into the plant tissue. Within 



