Pollen beetle but pollen is a major part of its diet. Several members of the Nitidulidae are similarly referred to as pollen beetles. In particular, practically all the species in the genus "Meligethes" are called pollen beetles. Of these the most notorious is probably the one now accepted as being properly called "Meligethes aeneus"/"Brassicogethes aeneus". It is called the "Brassica pollen beetle", "Rape pollen beetle" and similar names, because it first became prominent as a pest of such crops in the first quarter of the 20th century. Many species in the family Oedemeridae are similarly called "pollen beetles". For example, the Southern
Beta decay atoms obtain a more stable ratio of protons to neutrons. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. The binding energies of all existing nuclides form what is called the nuclear band or valley of stability. For either electron or positron emission to be energetically possible, the energy release (see below) or Q value must be positive. Beta decay is a consequence of the weak force, which is characterized by relatively lengthy decay times. Nucleons are composed of up quarks and down quarks, and the weak force