Carrot fly forecast 2025

The forecast outputs below are based on weather data provided by Agrii. The forecasts predict the timing of fly activity. They do not predict the number of insects present in the crop, as this depends on the size of the local fly population. For control purposes, we consider that the pest has become active when 10% of the insects have emerged/laid eggs and that the peak of activity has occurred when 50% have emerged/laid eggs. The predictions will change over time depending on weather conditions.

Third generation carrot fly activity may still be underway in a number of locations. It looks as if a proportion of these flies (the early ones) may have been able to mate and lay eggs (if they have access to a crop), whether their larvae subsequently cause damage will depend on future weather conditions.

Updated 17 November 2025

Location	First generation 10% eggs	First generation 50% eggs	Second generation 10% emergence	Second generation 10% eggs	Second generation 50% eggs	Third generation 10% emergence	Likelihood of eggs that might develop and cause damage
Cornwall - Hayle	28 Apr	11 May	19 Jul	28 Jul	9 Aug	21 Oct	Low
Kent - Sandwich	30 Apr	14 May	5 Jul	14 Jul	25 Jul	12 Sep	Some
Suffolk - Ipswich	3 May	15 May	10 Jul	18 Jul	30 Jul	16 Sep	Low
Warwick, Wellesbourne	30 Apr	16 May	4 Jul	12 Jul	27 Jul	10 Sep	Some
Norfolk, Norwich	5 May	18 May	12 Jul	20 Jul	1 Aug	21 Sep	Low
Lincolnshire - Holbeach	30 Apr	14 May	12 Jul	18 Jul	30 Jul	22 Sep	Low
Nottingham - Stubton	27 Apr	10 May	4 Jul	10 Jul	27 Jul	10 Sep	Some
Lancashire, Southport	1 May	19 May	14 Jul	18 Jul	1 Aug	29 Sep	Low
Yorkshire, York	1 May	15 May	6 Jul	14 Jul	27 Jul	15 Sep	Low
Perthshire, Scotland	5 May	20 May	19 Jul	27 Jul	11 Aug	-	-