The mason bee is common in spring. It can easily be identified by the thick layer of reddish brown hair that covers its thorax, the hairless blackish brown abdomen and reddish legs. Females have an abdominal broom. This is a structure formed by fringes of hair which is used to collect pollen.
This species is found in western counties of the Mediterranean including Portugal, Spain, France, Italy and Malta as well as North African counties as far east as Libya. In
it is restricted to southern Italy,
Sicily and Sardinia.
In Maltese the mason bee is known as naħla tal-koppla because of the rounded structure of its nest which looks like a church dome.
Mason bees are solitary bees but at this time of the year several can be seen close together on the ground especially in rocky areas, collecting gravel and small stones which they use to build their nests.
Females the building material collected from these places and cement it by mixing it with a secretion from their labial glands to form a mud. The mud is used to build rounded nests which are attached to walls or rocks. The labial secretion makes the dried mud impervious to water and the nest can last for many years.
The internal structure of the nest consists of several elongated cells which are filled with honey and pollen. An egg is laid in each cell. The larva forms a pupa which overwinters inside the nest. The adult bee emerges in early spring to start nest building and to collect pollen from flowers
The mason bee belongs to a family known as megachilid. Most bees belonging to this family are known either as mason bees or leafcutter leaves depending on the material they use to build their nests. A small number of species which collect plant or animal hairs and fibres are known as carder bees.
About fifteen species of megachiclid bees are found in the Maltese islands.
Megachiclid bees are inefficient pollen collectors. They have to visit several plants to collect sufficient pollen for their needs and this makes them very important pollinators.
This article was published in the Times of Malta on 16 April 2015.