Country diary: oilseed rape is a mixed blessing for bumblebees

Empingham, Rutland: The effects of mass-flowering crops are complex and there is often a twist in the tail for pollinators

Most of our 24 British bumblebee species follow the familiar stripy, mousy or red-tailed formats, but a few beautiful and rare ones are more distinctive. Darting between the honeysuckle flowers in an Empingham garden is a big bumblebee, sooty black from frons to tail. Bombus ruderatus subsp. perniger is a special form of the large garden bumblebee, its blackness never seen outside Britain.

When I first got to know this dark beauty, 25 years ago on south Cambridgeshire chalk, it was a rare beast heading towards extinction, but the species has since recovered a little, probably due to clover and vetch planted along arable field margins.