Possibly a county first
Description and notes
This mining bee has both a spring and a summer brood. These differ morphologically, especially in the male (for example, first brood specimens have a strong, conspicuous genal spine which is lacking in summer brood individuals of this sex). In addition, second brood specimens are often more extensively marked with red on the basal tergites and sternites than their spring counterparts. It is possible that these broods are actually distinct species and research, involving the cytogenetics of each brood, is still ongoing. Indeed, the first brood was formerly considered to be a separate species, Andrena spinigera
Status (in Britain only)
This species is not regarded as being scarce or threatened.
Generally distributed, having been recorded from coastal landslips and cliffs and, inland, from heaths, open woodland, chalk grassland, fens, commons and gardens.
Bivoltine; mid March to the end of April, and again from July to late September.
The species apparently nests singly, not in aggregations (Kocourek, 1966; Dylewska, 1987). In England, nests have been found in banks, slopes and bare vertical soil (e.g. Beavis, 2007). Communal nesting, as occurs in its close relatives, Andrena carantonica Pérez and A. bucephala Stephens, has not been confirmed for A. trimmerana.
It has been recorded from a buttercup, willows, bramble, rhododendron, blackthorn, gorse, alexanders and dandelion.
Nomada marshamella (Kirby) has been reported as a cleptoparasite of A. trimmerana (Perkins, 1919). Occasionally specimens are found which are stylopised, apparently by Stylops aterrimus Newport (Kinzelbach, 19