Excavator: Ground. Nesting aggregations are probably small and, despite the local abundance of this bee, are rarely found. Such an aggregation has been found in a roadside bank on Dartmoor, Devon (J.P. Field, pers. comm.). British nests have been described by Archer (1980).
A primitively eusocial species which in warm climates has a summer brood of workers. The latter are smaller than their mother. Brood cells are closed following provisioning and oviposition. Gynes and males emerge from mid summer to autumn. Males sometimes emerge from queen-built brood cells, but are usually raised from those provisioned by the workers. Mating occurs inside the nest. Mated females overwinter together. In cold climates (as on mountains in northern Japan) the species is solitary, with no worker brood (Sakagami & Munakata, 1972). Useful references to the biology and behaviour of this species are provided by Fabre (1879-1880), Bonelli (1965, 1968), Knerer (1968), Knerer & Plateaux-Quénu (1967), Plateaux-Quénu (1963, 1973, 1974, 1979), Poursin & Plateaux-Quénu (1982), Sakagami & Munakata (1972), and Vleugel (1961, 1973). Marikovskaya (1990) described nests excavated in unmetalled road in Kazakhstan in which all the nests were characteristically narrowed near the nest entrance (diameter up to 44.5mm). Around the nest entrance is a small mound made of excavated spoil. Sometimes the spoil is used to close the entrance during the night or in cloudy weather. The nests are excavated to a depth of 5 to 21cm, and the cells branch from a short corridor of some 4mm diameter arranged at a depth of 5 to 15cm. The length of the cells was approximately 10mm with a diameter of 6mm, narrowed at the mouth to 4mm. The provision is stored in the form of globular "pollen loaf" of 5mm diameter. The cell walls are longitudinally striated and covered with a glossy secretory film. In May (when most nests were only just established) only one sealed cell was found with an egg. The rest were empty or still unformed.
Many females were engaged in nest excavation. The nests were found on an exposed stony and clay road, as the surrounding roadside and the slopes of the gorge were covered in dense vegetation making them unsuitable for nesting. The nearest nesting aggregation to this was found only 100 metres away, so that the siting of these colonial nests is determined not only by features of the landscape, but also by behavioural characteristics of the species.
Males of this species frequently spend the night in clusters on low vegetation (sometimes in company with those of Lasioglossum albipes). O’Toole (1985) discovered that males of L. calceatum sometimes congregate in lek assemblages on flower heads. Here they constantly wheel about with their antennae erect and wings shivering. The wings are semi-iridescent when folded and this, together with a possible scent, is thought to attract the females. The latter hover around the flower head and dive into the cluster of males and are thus mated. It is not known how the female selects her mate. This is the first observation of lekking in a European bee. O’Toole’s description of this behaviour is accompanied by a photograph of a cluster of lekking males on a dead Centaurea flower head (O’Toole & Raw, 1991).