54 



This female consists of a globular body, the head, 

 thorax and abdomen more or less merging into one mass. 

 All that we need notice is the presence of the cornicles or 

 honey-tubes, the curious glands in the skin, the piercing 

 mouth and the two-jointed feet (Plate VIII., Fig. 7., the 

 upper right-hand Fig.) 



The cornicles are two tubular horns on the upper 

 surface of the abdomen, through which the insects pass 

 out a sweet, gummy excretion called " honey-dew." 

 Honey-dew is one of the causes of the dying of the 

 Rose leaves, for it falls from the Green Fly, covers the 

 leaves and prevents respiration. Later it becomes 

 covered with excrement and black fungus growth. 

 The glands on the back are also important to 

 remember, because it is through them that the skin 

 becomes covered with a mealy, waxy or thread-like sub- 

 stance that repels water, and hence, if we wish to corrode 

 the skin, we must use something that will hold the 

 corrosive substance. 



The structure of the foot at once separates the 

 Aphis or Green Fly from the Scale insect, which has 

 only one segment forming the foot. The respiration of 

 an Aphis is, as in all insects, by means of breathing 

 pores at the sides of the body. To kill them their pores 

 must be closed by some sticky substance. One of the 

 most remarkable things in the bionomics of the Aphides 

 is the extraordinary rate and method of reproduction. 



During a great part of their life-cycle they reproduce 

 asexually, that is without the presence of a male Aphis. 

 This method of producing their progeny alive is called 

 parthenogenesis. It may continue for several generations. 

 The young themselves soon reach sexual maturity and 

 reproduce again. 



