The ‘humble bumble’ (Bombus humilis), together with about half of the British species of bumblebee, has suffered a drastic decline in range in recent decades. Its conservation is addressed nationally by a UK Species Action Plan. The humble bumble is somewhat smaller than the common garden bumblebee (B. terrestris), and has a fairly uniform, golden colour.

In London as a whole the species is rare, though it remains widespread in suitable habitat along the East Thames Corridor, especially on the Essex side. The humble bumble has been recorded from the London Boroughs of Barking and Dagenham, Bexley, Newham, Tower Hamlets and Havering and most records are from flower-rich wasteland near the tidal Thames. As the species is absent from some apparently suitable sites further inland, coastal influence is likely to be a key element of its habitat requirements.

Bombus humilis has no universally-accepted English name. One translation of its specific name from the Latin is ‘humble bumble’, hence the name we use in this Statement for the sake of convenience. The bee is a member of two groups of species known as long-tongued bumblebees and carder bees.

The decline in the humble bumble’s range throughout the 20^th century, where it had disappeared from most of its northern and inland sites by the early 1960s, has been attributed to habitat loss through the development of modern agricultural practice. The mechanisation of hay-making and, later, the shift to silage making, has resulted in a restricted distribution, now concentrated mainly on the East Thames Corridor, south-western coasts of England and southern coast of Wales.

Both nationally and in the London area, the changes in population and distribution of the bumblebee have been like a ‘miner’s canary’, reflecting significant rural and urban environmental changes over the last half-century.

The humble bumble is associated with flower-rich habitats, but uses a surprisingly restricted range of species for foraging, notably certain perennial, deep-rooted members of the pea and dead-nettle families. The right combination of conditions is usually found in London’s wasteland sites, otherwise known as ‘post-industrial wasteland’. These sites are usually unmanaged and are often characterised by their sandy substrates, open conditions and low nutrient status.

This bumblebee appears to be able to survive on long, narrow mosaics of habitat better than other threatened bumblebees. However, the bee’s nesting density is low so it needs a large area of land to support a viable colony. Narrow habitat-mosaics are unfortunately particularly vulnerable to fragmentation.

In East London, the decline of the humble bumble is overwhelmingly the result of wasteland loss to development. The continuing pressures to develop on such sites constitute by far the greatest threat to the species in the London area – particularly at its Thames-side locations.

Habitat management can be of benefit in some cases, particularly on sites whose clay substrate and higher nutrient status encourages plant growth. In these areas, phased removal of vegetation on a long rotation, or disturbance management, is essential to prevent the development of a sward dominated by false oat-grass, which crowds out the bumblebee’s wildflower foraging resources. Regular or frequent cutting, however, can be catastrophic.

There are five broad actions that could benefit the humble bumble. Most of these are inter-dependent.