Photo: Michael Becker / CC BY-SA 3.0

Colletes daviesanus

Davies' Colletes

A medium-small plasterer bee (7–9 mm) with dense brownish hairs on the thorax, a shiny black abdomen with broad pale marginal hair bands, and a characteristically short, bilobed tongue. The first tergite is notably sparsely punctate and glossy, a key distinguishing feature among banded Colletes. It is an oligolectic specialist on Asteraceae, gathering pollen almost exclusively from flowers such as tansy (Tanacetum vulgare), yarrow (Achillea millefolium), oxeye daisy (Leucanthemum vulgare), and chamomiles. It nests in large aggregations within vertical earth faces, soft sandstone cliffs, loess walls, and even mortar joints of old buildings, earning it notoriety as a minor structural pest where it occurs in high densities. It is a synanthropic species that has adapted well to human settlements. In Switzerland it is widespread and common in sand pits, quarries, vineyards, ruderal areas, and villages. The cleptoparasitic bee Epeolus variegatus attacks its nests. Flight period is univoltine from mid-June to late August. Swiss Red List: Near Threatened (NT).