Bearberry

Bearberry (Arctostaphylos uva-ursi) in Scotland acts as a food source for several specialized moth larvae and is pollinated by insects such as bees and thrips. Key insect herbivores and pollinators associated with bearberry in Scotland include:

Larvae Feeding on Foliage and Shoots

• Netted Mountain Moth (Macaria carbonaria): A rare and declining moth found in the Scottish Highlands, with bearberry as its sole caterpillar foodplant.

• Small Dark Yellow Underwing (Anarta cordigera): A moth restricted in the UK to the Scottish Highlands, whose larvae feed exclusively on bearberry leaves and young shoots from late May to mid-July.

• Broad-bordered White Underwing (Anarta melanopa): Another specialist moth in the Scottish Highlands that feeds on bearberry, as well as bilberry and crowberry.

• Epinotia nemorivaga: A small moth found from Perthshire northwards in Scotland whose larvae feed within spun bearberry shoots.

• Coleophora arctostaphyli: A leaf-mining moth whose larvae live in a protective case and eat plant tissue, recorded on bearberry in northern Scotland.

Pollinators and Other Associations

• Bees: The urn-shaped, waxy flowers blooming from April to June are pollinated by bees.

• Thrips: In addition to bees, thrips have been identified as pollinators for bearberry, particularly in northern latitudes where they are active early.

• Aphids: Various aphid species (sap-sucking bugs) are known to be associated with heath plants like bearberry in Scotland. 

The Cairngorms National Park is considered a stronghold for many of these insects.

Bearberry (Arctostaphylos uva-ursi) prefers well-drained, acidic (pH 4.5–5.5), sandy, or rocky soil, thriving in poor, nutrient-deficient conditions. They require excellent drainage, making sloping, sandy sites or rock gardens ideal to prevent root rot. Avoid heavy, clay-rich, or overly fertile, lime-filled soils.

Ideal Soil Characteristics for Bearberry:

• pH Level: Highly acidic, ideally between 4.5 and 5.5.

• Drainage: Fast-draining soil is essential to prevent root rot, as they are susceptible to wet conditions.

• Texture: Sandy, gravelly, or rocky soil types are best.

• Nutrients: Thrives in nutrient-poor ("barren") soil.

• Moisture: Prefers dry to medium moisture levels.

In Scotland, bearberry (Arctostaphylos uva-ursi) is widespread and abundant in upland areas, typically thriving at mid-elevations in the Highlands, but it can be found from sea level up to around 700-900 meters.

• Low Altitudes: In the west of Scotland, it is known to grow right down to sea level, often found on exposed coastal sites where strong winds, thin soil, or gravelly, rocky conditions allow it to compete.

• High Altitudes: While more common at lower and mid-elevations, it can still be found in the mountains, with records indicating it grows up to approximately \(710\)m on Rannoch Moor and even higher in other parts of the Western Highlands, reaching heights up to \(915\)m.

• Habitat: It prefers open, acidic, and well-drained habitats like heathery slopes, stony ground, and pine woodlands.