Shrill carder bee  (Bombus sylvarum)

Classified as Endangered in the UK.

The shrill carder bee is one of the smaller members of the bumblebee family. It has a distinctive combination of markings, being predominantly grey-green, with a single black band across the thorax, and two dark bands on the abdomen. The tip of the abdomen is pale orange. The queens fly very quickly and produce an audible high-pitched buzz. Although workers and males fly equally fast, they appear to be far less noisy. The combination of rapid flight and distinctive colouration make this species fairly easy to identify.

The shrill carder bee is found throughout Europe and is declining throughout its range. In the UK, it was considered a common species in the 19th century and the early part of the 20th century. However, records since 1970 indicate that it has declined drastically in the UK, and is now only known from seven populations. These are in Kent, Essex, Wiltshire, Somerset and South Wales.

This bee is an insect of extensive areas of herb-rich grassland of the sort that used to be widespread in Britain. Today, populations are restricted to large military ranges, unimproved pasture across the Somerset Levels, and brownfield sites along the Thames corridor.

Formerly common and widespread meadow and hedgerow plants with long corollas, such as vetches, clovers, dead-nettles and the red bartsia, are essential sources of pollen and nectar. It has been estimated that, to remain viable, individual bee populations require an area of suitable habitat of at least 10 square kilometres. Nectar and pollen supplies need to be available throughout the bee’s flight period of April to September.

Queens emerge from hibernation in mid to late April. Nests are constructed from grass stems and other dead vegetation, either on the surface or slightly below ground. The old nests of mice or voles sometimes form the foundation, and the colony may only number fewer than 100 workers. However, nests can survive until late September.

The loss of unimproved flower-rich grasslands, unploughed and unsprayed field headlands and hedge banks, as a result of agricultural improvement and intensification, has been the major cause for the decline of this and many other species of bumblebee. Heavy and continued grazing of flower-rich sites also poses a threat, and the existing populations along the Thames corridor are presently being threatened by proposed development.

The shrill carder bee is listed in the UK Biodiversity Action Plan (UKBAP) and is included on English Nature's Species Recovery Programme. It is one of several species of bee that is threatened in Britain, and in 1998, the UKBAP Bumblebee Working Group was set up to discover more about the status of many endangered bees. The group consists of seven conservation bodies, including three of the UK statutory bodies; English Nature, Countryside Council for Wales and Scottish Natural Heritage.

Survey work has begun to establish the true numbers and ranges of several species of bumblebee, and the working group has published a series of recommendations for restoring the bee's populations. These include encouraging the practice of leaving field margins undisturbed and free from herbicide and pesticide treatment, the re-creation of herb-rich meadows, and the modification of grazing regimes on existing grassland. They also suggest modifying the grazing patterns on existing grassland, and erecting artificial nest boxes to encourage queen bees to start a colony.

The UK Biodiversity Action Plan for this species is available at UK BAP.