Birth

• http://en.wikipedia.org/wiki/File:Aphid-giving-birth.jpg
  
  In the spring and early summer, greenflies give birth to live young without mating. The nymphs are all females. At the time they are born, they are alive but surrounded by a transparent capsule.
  
  

Nymphs

• The wingless female nymphs, whether reproduced in live birth or from the spring hatching of the autumn generation of eggs, are similar in appearance to an adult greenfly. They will not enter into a larval or pupal stage as many insects do but will molt several times before becoming adult females. Nymphs mature to adulthood and give birth to the next generation within eight to ten days.
  
  

Winged

• http://en.wikipedia.org/wiki/File:Aphids_feeding_on_fennel.jpg
  
  Winged greenflies are produced when there are predators in the area or when the population is ready to move to a different host. Once the greenflies are settled on a new host, wings are lost.
  
  When males are produced, in late summer and early autumn, they are winged.
  
  

Mating

• The females continue to produce more offspring throughout the summer. As the days grow colder and shorter, the females will produce male as well as female offspring. Toward the end of the season, the males and females will mate.
  
  

Eggs

• This mating will produce the only eggs of the season, which the females will lay on host plants. When laid, the eggs are black, with thick shells that can withstand winter temperatures. These eggs will hatch in the spring, and wingless female nymphs will emerge.