Carrot Fly

photo: gardenofeaden
Carrot Fly.
  • Binomial name:                       Chamaepsila rosae.
  • Family:                                      Psilidae
  • Small black bodied female carrot flies emerge from their pupae in spring, mate and lay their eggs in soil close to young carrots.  
  • Once hatched, carrot fly larvae find a suitable carrot plant and burrow into its roots.  
  • After reaching full size, they retreat to the soil to pupate and overwinter until the next spring when the cycle starts again.
Why Carrot Fly are a Pest.
  • Creamy/yellow carrot fly larvae leave a trail of rusty blown discolouration on the surface of carrots and in the tunnels they make in the carrots root.  They grow to a fully mature size of about 10mm long.  A heavy infestation can ruin a crop of carrots.
Pest Control.
  • A 4 year Crop rotation is a very important way of reducing the impact of carrot flies.  By moving the carrots to a new bed each year, the carrot fly maggots are deprived of a food source.
  • Carrot flies fly close to the ground and raised garden beds are a significant barrier to them finding new plantings of carrots. 
  • Ecobed pest exclusion netting keeps carrot flies out of new beds.  See my website "Gardening with Ecobeds" for information on making your own raised garden beds equipped with efficient pest exclusion frames.
  • Sow carrot seeds thinly to reduce the amount of thinning you have to do.  When you do thin out your crop, cover any exposed roots with soil and dispose of thinnings immediately.  You need to do this because the carrot fly is attracted by the scent of the exposed carrot root.
  • The onion family (alliums) are said to be good companions for carrots as their smell confuses the carrot fly when looking for new hosts.   This is handy since they belong to the same group in my crop rotation and are always grown together in an Ecobed.
  • Good soil management can help control carrot fly.  Steinernema spp, a predatory nematode which is common and lives in biologically active soil kills the carrot fly larvae.
  • I understand Steinernema Spp is commercially available, but I rely on generous applications of home made compost and aerated compost extract to maintain high biological activity in my soil.
  • Since carrot flies are said to only lay their eggs on bare soil, the use of mulch carefully applied around the carrot plants should interrupt their reproductive cycle.