390 TEXT-BOOK OF ZOOLOGY 



through the body wall), from which in the autumn or the succeeding 

 spring one of the early unwinged females (u.W.) is produced. 



A far more destructive species is the Vine Aphis (Phylloxera 

 vastatrix). This insect originates from America, but is continuing to 

 spread over Europe, and in many districts has almost totally ruined 

 the vine culture. The reproduction of this injurious insect is very 

 complicated. From the winter eggs are produced wingless females 

 (u.W.) ; these produce a number of eggs, which again give rise to 

 wingless females. This process is repeated from six to eight times in 

 the course of the summer. The large number of plant lice produced 

 in this manner suck at the fine root fibres of the vine, producing 

 swellings, A., and .so disturbing the functions of the root as to bring 

 about the final destruction of the plant. Among these "root lice," 

 winged individuals (g.W.) are also produced, which leave the soil and fly 

 to other vines, on which they deposit a few very large eggs. These 

 latter give rise to wingless males and females. The latter each lay a 

 single egg, which is one of the "winter eggs" referred to above. Un- 

 fortunately, no means have hitherto been discovered of destroying this 

 pest without at the same time ruining the vines. 



Family 2 : Scale Insects (Coccidae). 



Upon vines, stone-fruit trees and greenhouse plants, we often meet 

 with shield-shaped brown structures which one would hardly suspect to 

 be of animal nature. They are the females of Scale Insects which 

 have inserted their beaks into the plant. These insects die in this 

 position, and then serve as a protecting roof to their eggs, which are 

 found beneath them in the form of a white powder. The males have 

 somewhat the shape of an aphis, and are winged and active creatures 

 (why is it necessary that they should be such ?). 



The Cochineal Insect (Coccus cacti), which lives on various cactus 

 plants, furnishes, when dried, the valuable red pigment known as 

 cochineal or carmine. It is a native of Mexico, but has for many years 

 been cultivated in Algiers, the Canary Islands, and other localities. 



The Lac Insect (C. lacca) of India, by puncturing fig-trees, produces 

 the flow of a resinous juice from which shellac is obtained. 



Sub-Order 4: Wingless Rhynchota or Lice (Aptera). 



The members of this group are wingless parasites. The Lice 

 (Pediculidce) are blood-suckers furnished with an (introvertible) pro- 



