More on aphids

[Richard Winder]

A further clarification on the information I posted on aphid
congregation on maize grown in the field...  My wife, a horiticultural 
expert, was paying much closer attention to the speaker I referred to-
the crop was fava beans, not maize.  The main reasons she cites for aphid 
congregation are:

1) Genotypic variation

2) Phenotypic variation (often nitrogen-induced succulence)

3) Parthenogenesis (previously mentioned in another post)

4) Ant herding

She felt that the cause was genotypic in this case- the farmer is principally
growing many varieties of seed w/ open pollination.   -RSW

  RICHARD WINDER                    Title: Visiting Fellow
  Forestry Canada                   Phone: (604) 363-0600
  Victoria, B.C.                    Internet: RWINDER at A1.PFC.Forestry.CA