Largest bumblebee species

The world's largest species of bumblebee is the giant bumblebee Bombus dahlbomii, native to Patagonia in southernmost South America. The ginger-furred queens of this species measure up to 4 cm in length, and have been likened to flying mice. The giant bumblebee once ranged across thousands of kilometres in Patagonia, and is the only native bumblebee in South America's temperate forests, but in recent years it has become very rare and experts fear that it faces extinction in the near future. The reason for this spectacular species' dramatic decline is believed to be a unicellular bee parasite, Apicystis bombi, spread by the European white-tailed bumblebee B. terrestris. The European species was introduced into Chile in 1997 to pollinate agricultural crops, but subsequently spread into Patagonia, where researchers had formally documented it by 2006 – the same time that the giant bumblebee (formerly the only bumblebee species anywhere in Patagonia) began to decrease in numbers.