APHIDES 385 



stage, is wholly dependent on the ants. It lives 

 in the ground, and is carried from the ants' nest 

 to the roots of the plants on which it feeds, and is 

 carried back again to the safety of the nest when 

 feeding-time is over. 



The life history of these interesting insects is 

 most remarkable, and in some species at least is 

 not properly understood. 



Life History of the Common Aphis. 



Commencing from the eggs, which are laid in 

 the autumn, numerous wingless virgin females arc 

 produced. These in turn produce (within a few 

 days), not eggs, but wingless young. This pro- 

 ducing of young without direct fertilisation is 

 termed ^^ parthenogenesis.^^ These daughter aphides 

 again in a few days produce young, and so on; so 

 that one can see why tliese insects are such plagues, 

 for they are so numerous. 



Usually later, true males and females are hatch- 

 ed. These are often winged, but may be wingless. 

 We have noted winged forms on tips of rose shoots 

 in July and August and during very cold weather on 

 the coast. The true females deposit eggs, which re- 

 main in crevices over the winter. From these 

 eggs the virgin females hatch. Some species of 

 aphides hibernate during the winter, hiding in crev- 

 ices in stems and on roots. Orchardists have found 

 that treating the soil around the tree with kerosene 

 emulsion or with tobacco solution gives good result. 

 Spraying leaves and branches with these solutions 

 is also good. 



The woolly aphis excretes a white, woolly sub- 

 stance, with which it conceals its body. The 



