In 1957, MacLeod and Donnelly estimated the local population density of C. vicina in an area near Carlisle to be:
A latter study by the same team in 1962 found local aggregations, or clusters, of blowflies. Many were associated with particular habitat features but many were not.
It is also clear that when conditions are good, blowfly populations often become over crowded, leading to a subsequent fall in population numbers as competition for the available carcasses outstrips supply.
Calliphora vicina is considered to be highly synanthropic in most parts of its range. Overall numbers have probably increased over recent centuries in association with human populations.
Existing management practices are aimed at killing or excluding blowflies (for example, by fly screening) so that they, and others with similar feeding habits, don't impact on food hygiene standards.
Synanthropic
Associated with humans.