Bumblebees mostly fall into two distinct genera, the parasitic Psithyrus  and the nest-building Bombus.   They are social insects and live together in colonies of between 50-400 bees,  usually with only one queen. They are very charismatic and are large and fuzzy with short, stubby wings, which they can flap at around 200 times per second. This rapid beating, combined with their large bodies, vibrates flowers until they release pollen, which they chew and mix with their saliva to make honey. Bumblebees are excellent pollinators which is vital as two-thirds  of the world's crops depend on cross fertilisation. Infection carried by commercially bred bees, the overuse of dangerous  pesticides, extreme habitat loss and the climate change crisis are all  contributing to the rapid decline of the bumblebee population .