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Research case study - control of carrot fly

Larvae of the carrot fly (Psila rosae) damage the roots of carrot, parsnip and other related crops such as celery, celeriac and parsley. Over the years, researchers at Warwick (formerly NVRS and then Warwick HRI) have studied various approaches to managing carrot fly in conventional and organic crops.

This has included methods of monitoring carrot fly with yellow sticky traps and improving trap selectivity to make it easier to identify the carrot flies and reduce the numbers of non-target insects captured. Studies on trap orientation shoed that the greatest numbers of Psila rosae were caught on the lower surface of traps inclined to 45° to the vertical with the sticky surface facing downward, whilst the numbers of ‘non-target’ species were reduced compared with traps aligned vertically. This technique has been adopted elsewhere.

FINCH, S. & COLLIER, R.H. (1989). Effects of the angle of inclination of traps on the numbers of pests and beneficial Diptera caught on sticky boards. Entomologia experimentalis et applicata 52, 23-27.

Other studies have considered the use of physical barriers to exclude carrot fly adults from susceptible crops, either crop covers or ‘fences’.

Over the last decade or so carrot growers have relied on one group of insecticides (pyrethroids) to control carrot fly. Research undertaken at Warwick, with funding from the HDC, identified the best treatment timings for foliar sprays of pyrethroids. There are now some new active ingredients with activity against carrot fly and these are being investigated further with HDC funding. A carrot fly forecast, developed with funding from Defra and the HDC, can be used to indicate when carrot flies will be active in different parts of the UK. Output from the forecast currently forms part of the HDC Pest Bulletin on the Syngenta web site.

Researchers at Warwick (then Warwick HRI) have also been involved in the search for sources of resistance to carrot fly in carrot. Material produced some years ago led to varieties such as Flyaway and Resistafly. Warwick Crop Centre is now involved in a Technology Strategy Board project to identify further sources of resistance.




Adult carrot fly


Sticky traps to monitor carrot fly


Fence to exclude carrot fly