Cheilosia mutabilis (Fallén, 1817)
Biology & ecology:
The larva has been found in the roots of Welted Thistle Carduus crispus, but as this is not a heathland species and C. mutabilis is also known from heathland, it must be assumed that a variety of host thistles are utilised. Adults rarely occur in numbers, most frequently being found as single individuals.
Widely distributed as far as northern Scotland but with very noticeable concentrations of records in South Yorkshire and Derbyshire. Elsewhere, records are mainly scattered and offer no obvious pattern.
Status & conservation:
There has been a significant decline in occurrence from most parts of Britain over the past 25 years. These changes may to be an artefact of recorder effort because relatively few modern recorders report the Cheilosini: the data may be skewed as a result. Recorded from 53 hectads since 1985.