from how far can flies smell food?

Question: from how far can flies smell food?
- Keywords:
  fly,
  food,
  smell
Asked by thing2oxo to Ed, Hayley, Jason, Nathan, Sophie on 20 Mar 2013.
- Hayley Evers-King answered on 20 Mar 2013:
  
  Experiments have found that in good weather conditions, flies can smell food from up to 7km away! It certainly feels like that here – it’s summer at the moment in South Africa and every time we have a BBQ so many flies arrive!

Question: from how far can flies smell food?