The timing of the migration ofAphis fabaeat any location can be predicted using the mean air temperature and the site’s latitude and longitude. A range of equations were produced in AHDB Project FV 407adescribing the relationships between the dates of first, 10% and 50% capture of aphids in suction traps and the mean air temperature over different periods and site latitude and longitude.

Forecast based on air temperatures (January-April)

	First	10% aphids	50% aphids
Cornwall	18-May	13-Jun	10-Jul
Kent	13-May	22-Jun	10-Jul
Suffolk	13-May	24-Jun	11-Jul
Wellesbourne	23-May	27-Jun	17-Jul
Norfolk	18-May	29-Jun	15-Jul
South Lincs	25-May	2-Jul	20-Jul
Nottingham	27-May	2-Jul	21-Jul
Lancashire	4-Jun	5-Jul	26-Jul
York	3-Jun	9-Jul	26-Jul
Scotland	2-Jun	17-Jul	31-Jul