698 



CLASS IV. INSECTA. 



body. Psylla 

 secretes " honey - 

 de w ' ' in su ch 

 quantities that it 

 has given rise to 

 the legends of 

 weeping trees. 

 Some species form 

 galls, e.g. Pachy- 

 psylla. 



Fam. 7. Aphidae.. 

 Minvite insects. No 

 ocelli. When pres- 

 ent the four pair of 

 wings are transpar- 

 ent. Antennae 3- 

 to 7-seg m e n t e d. 

 Frequently a pair 

 of processes is borne 

 on the dorsal sur- 

 face of the 5th ab- 

 dominal segment. 

 Plant-lice abound 

 both in species and 

 individuals. They 

 are soft bodied and 

 often coated with a 

 waxy "bloom" 

 secreted by 



certain glands (Fig. 443). The young differ but little from the parents. 

 All through the summer the females reproduce parthenogenetically 

 and viviparously, and as their young are all females and are capable of 



FIG. 442. Psylla succinta. x 15. Europe (after Heeger. 

 From Sharp). A larva before first moult ; B larva after third 

 moult; C adult. 



(L 



FlG. 443. The wax glands and the prominences on which they open of one of the Aphidae 

 (Schizoneura Lonicerae). a pupa seen from dorsal surface ; Wh prominences on which 

 the wax glands open ; b the unicellular wax glands WD beneath the cuticular facets 

 Cf of the skin. 



producing offspring in a few days, plant-lice multiply exceedingly. 

 Sooner or later and generally towards the autumn, the plant-lice pro- 



