420 



AN INTRODUCTION TO ENTOMOLOGY 



long, narrow stig- 

 ma (Fig. 492). In all 

 other living aphids 

 the origin of the ra- 

 dial sector is much 

 nearer the tip of the 

 wing; but in many 

 of the fossil aphid 

 wings it is as in 

 Mindarus . The 

 males and the 

 oviparous females 

 are small and wing- 

 less; but they retain the beak, at least in most individuals, and feed. 

 The female lays several eggs. 



Only one species, Mindarus ahietinus, is known. This lives free 

 upon the twigs of spruce and other conifers, which become somewhat 

 distorted and are often killed by the attack of the insects. When 

 disturbed this insect secretes large quantities of honeydew. 



The life-cycle of this species usually includes only three genera- 

 tions, the stem-mother, the winged agamic females {sexuparce), and 

 the sexual forms. Sometimes there is a generation of wingless 

 agamic females. 



This species was redescribed by Thomas as Schizoneura pinicola. 



Fig. 492. — Wings of Mindarus. (After Patch.) 



Subfamily ERIOSOMATIN^ 



This subfamily includes those genera of aphids in which the males 

 and the oviparous females are greatly specialized by reduction. They 

 do not have functioning mouth-parts; some have a beak when born 

 but lose it at the first molting; in others the beak is vestigial at birth. 

 As they cannot feed, they remain small. Both sexes are wingless. 

 The oviparous females produce each a single egg, which in some 

 species is not laid but remains throughout the winter in the shriveled 

 body of the female. 



In this subfamily, the cornicles are much reduced or are wanting ; 

 wax-glands are abundantly developed; and the antennal sensoria are 

 prominent. These are often annular. 



The members of this subfamily that are most likely to attract 

 attention can be grouped under two heads: a, the woolly aphids; 

 and b, the gall-making Erisomatinse. These groups, however, do not 

 represent natural divisions of the subfamily and do not include all 

 members of it. They are merely used for convenience in the present 

 discussion. 



a. THE WOOLLY APHIDS 



The woolly aphids are the most conspicuous members of the 

 Aphididae, on account of the abundant, white, waxy excretion that 



