Bees, ants and wasps

To read more please go to the Sidmouth to Dorset coastal wildbelt group page. 

Two species, the brown-banded carder bumblebee and the moss carder bumblebee, are listed as Focus Species. They’ve undergone a serious national decline since the 1970s and the Devon populations are nationally important.   

Carder bumblebees need a range of flowering plants, in particular those with long tubular flowers (they have long tongues) but also clovers, peas, mint, figwort and the daisy family. Both species nest on or just below the ground among long grass or mossy vegetation. They have a clear preference for extensive, well-connected flowery habitats with rough grasslands.  

This wasp is restricted to heathland sites across southern England, from Devon to Sussex. In Devon it’s only known to be in the Pebblebed and Bovey Basin heaths.   What do we need to do to expand the population to other heaths with suitable habitat?  How well do they disperse?  

Heath potter wasps are known for (and named after) the unique vase-like structures the females build to lay their eggs in. To build the 10-25 pots she will make in her short lifetime (just two to three months), the female needs a site that has water and clay, with heather, gorse and grass nearby. Females lay an egg inside each pot and add up to 38 moth caterpillars, creating a larder for the wasp larva when it hatches. Moth species the wasps prefer are the double-striped pug (Gymnoscelis rufifasciata) and the narrow-winged pug (Eupithecia nanata), which feed on gorse, heather and holly. 

The narrow-headed ant is endangered. In the UK it’s only found in Devon at Chudleigh Knighton Heath SSSI and the adjacent road verges, and at a few sites in the Scottish Highlands. 

The ants build south-facing domed nests, typically in tussocks of grass on the edge of heathland. Their nests are often close to trees, on which they ‘farm’ aphids. The ants herd the aphids towards food and protect them from predators. In turn, the aphids allow the ants to feed on the sugar-rich honeydew they secrete.  

The species lives in small colonies, which means the ants can quickly dismantle their nests and move to a sunnier spot, or set up temporary satellite nests to take advantage of seasonal resources. This makes it hard to monitor where the ants are.  

Habitat loss and fragmentation mean the species cannot naturally disperse in Devon. Threats include scrub encroaching onto nesting areas and nests being destroyed when verges are cut. A potential future threat comes from mineral extraction rights at Chudleigh Knighton Heaths.  

This bumblebee is also known as the mountain bumblebee as it’s found in uplands among habitat mosaics of flower-rich grassland and heathland with bilberry.  

Bilberries are particularly important in spring when the queens first fly. However, other key plants for the species include willow, bell heather, bird’s-foot trefoil, clovers and bramble. Bilberry bumblebees nest in old mammal burrows in fairly small colonies of around 50 workers. 

Once widespread, the bee is now facing serious declines. This is thought to be due to habitat loss and its vulnerability to climate change, as the bee is dependent on high altitude habitats and has a low heat tolerance. The bilberry bumblebee is a great indicator of a healthy, wildlife-rich upland landscape.  

Devon has two of the few upland moorland areas in the south of England making it of national importance for the species. Little is known about the bilberry bee in Devon other than ad hoc records from the edge of Exmoor and around Castle Drogo, Hembury and Parke on Dartmoor.