Lasioglossum malachurum is a small European halictid bee. This species is eusocial, with queens and workers, though the differences between the castes are not nearly as extreme as in honey bees. Early taxonomists mistakenly assigned the worker females to a different species from the queens. They are small (~1 cm), shining blackish bees with whitish hair bands at the bases of the abdominal segments.
Lasioglossum malachurum tend to nest in aggregations in favourable locations, where bees individually excavate separate nesting burrows close together in hard soil. These aggregations, sometimes containing hundreds of burrows, are not "colonies", as each nest burrow is distinct from another; each burrow contains a separate colony. They feed on pollen and nectar, mainly collected from the flowers of willows and dandelions when they are in flower in the spring.
The queens of L. malachurum, following fertilisation the previous year, begin to appear in the spring, when plenty of food sources are available to sustain them after the long overwintering period. Although several females usually see out winter in the same burrow with little conflict, they now act aggressively until a single female is left in possession of the burrow, leaving the evicted females to obtain or excavate burrows of their own.
Each female in possession of a nest tunnel then begins to build brood cells in short side passages which she excavates to the side of the main passage. Immediately following construction each brood cell is mass-provisioned with a mixture of pollen and nectar in the form of a firm, doughy mass. An egg is laid on each pollen mass and the individual cell sealed by the female. She then goes on to construct more, similar cells containing eggs and pollen masses.
By the end of May, larvae from the earliest eggs are full grown and start pupation, emerging from their cells by mid-June. These adults are all non-reproductive females, somewhat smaller than their mother.
The original maternal female bee remains within the nest and guards the entrance to the burrow, now acting as a queen while her non-reproductive daughters act as workers; they go out foraging for food, and help in the construction of new brood cells, which the queen lays new eggs in.
By the beginning of August reproductive females, the same morphology as their mother, and some males begin to emerge from this second set of egg. During sunny weather, the males mate with the new reproductive females (from both their own and separate nests), although they do not attempt mating with the non-reproductive females. Impregnated females may continue to live in their mothers' nests, although it is thought that they only forage for their own food and do not contribute to the rest of the nest.
With the arrival of the colder autumn weather the males and non-reproductive females die off, and the impregnated reproductive females go on to spend the winter in diapause and repeat the life cycle the following year.
The life cycle is longer, with two successive broods of workers, farther south in Europe where conditions are warmer and the season longer.
- L. M. Wyman & M. H. Richards (2003). "Colony social organization of Lasioglossum malachurum Kirby (Hymenoptera, Halictidae) in southern Greece" (PDF). Insectes Sociaux 50 (3): 201–211. doi:10.1007/s00040-003-0647-7.