The graph below shows the ‘day-degree forecast’ for willow-carrot aphid (Cavariella aegopodii). The forecast is based on accumulated day-degrees (D°) from 1 February (base 4.4°C). Information from the Rothamsted Suction trap captures have been used to estimate the mean number of D° from 1 February until the first aphid of the year is caught in a suction trap (the start of the migration to carrot) and when 10% of aphids are caught. This is after approximately 325 and 451D° respectively.

Forecast updated on 21st April 2022.