The Calliphoridae (commonly known as blow flies , blow-flies , carrion flies , bluebottles or greenbottles ) are a family of insects in the order Diptera , with almost 1,900 known species. The maggot larvae, often used as fishing bait, are known as gentles . The family is known to be polyphyletic but much remains disputed regarding proper treatment of the constituent taxa, some of which are occasionally accorded family status (e.g., Bengaliidae and Helicoboscidae).