 Bumblebee species are declining in Europe , North America , and Asia due to a number of factors , including land @-@ use change that reduces their food plants . In North America , pathogens are possibly having a stronger negative effect especially for the subgenus Bombus . A major impact on bumblebees was caused by the mechanisation of agriculture , accelerated by the urgent need to increase food production during the Second World War . Small farms depended on horses to pull implements and carts . The horses were fed on clover and hay , both of which were permanently grown on a typical farm . Little artificial fertiliser was used . Farms thus provided flowering clover and flower @-@ rich meadows , favouring bumblebees . Mechanisation removed the need for horses and most of the clover ; artificial fertilisers encouraged the growth of taller grasses , outcompeting the meadow flowers . Most of the flowers , and the bumblebees that fed on them , disappeared from Britain by the early 1980s . The last native British short @-@ haired bumblebee was captured near Dungeness in 1988 . This significant increase in pesticide and fertilizer use associated with the industrialization of agriculture has had adverse effects on the Bombus <unk> bees are directly exposed to the chemicals in two ways : by consuming nectar that has been directly treated with pesticide , or through physical contact with treated plants and flowers . The species Bombus <unk> in particular has been found to be impacted by the pesticides ; their brood development has been reduced and their memory has been negatively affected . Additionally , pesticide risk pose consequences colony development and size . 
