142 



ANIMAL LIFE 



piercing ovipositors, by means of which the eggs are de- 

 posited in the ground or in the leaves or stems of green 

 plants, or even in the hard wood of tree-trunks. Some of 



the scale insects se- 

 crete wax from their 

 bodies and form a 

 large, often beautiful 

 egg-case, attached to 

 and nearly covering the body in 

 which eggs are deposited (Fig. 

 79). The various gall insects lay 

 their eggs in the soft tissue of 

 plants, and on the hatching of 

 the larvae an abnormal growth 

 of the plant occurs about the 

 young insect, forming an in- 

 closing gall that serves not only 

 to protect the insect within, 

 but to furnish it with an abun- 

 dance of plant-sap, its food. The 

 young insect remains in the gall 

 until it completes its develop- 

 ment and growth, when it 

 gnaws its way out. Such insect galls are especially abun- 

 dant on oak trees (Fig. 80). The cafe of the eggs and the 

 young of the social insects, as the bees and ants, are de- 

 scribed in Chapter IX, 



Fia. 7'9 The cottony cushion scale 

 insect (Icerya purchasi), from 

 California. The male is winged, 

 the female wingless and with a 

 large waxen egg-sac (e.s.) attached 

 to her body. (The lines at the left 

 of each figure indicate the size of 

 the insects.) 



