THE SELECTIVE USE OF FLORAL RESOURCES BY THE HOVERFLY EPISYRPHUS-BALTEATUS (DIPTERA, SYRPHIDAE) ON FARMLAND

The use of flowers of non-crop plants by the syrphid Episyrphus balteatus in margins of cereal fields was assessed quantitatively. G-tests and the 'C' index of Murdoch (1969) were used to compare the use and abundance of twenty-seven plant species by adult flies from June to August in the UK. The flowers of several plant species were used selectively by hoverflies throughout the season while the relative importance of others changed with date. The prospects for managing the field-margin flora to enhance biocontrol by hoverflies is discussed.