Staff in environmental health jobs with Barrow Borough Council are working with the Environment Agency (EA) to try and determine the cause of a fly infestation at a business park.
The Sowerby Woods Business Park is home to 15 companies, most of which have been suffering with the problem for the past few weeks.
Bob Kett, owner of Furness Plastics, told the North-West Evening Mail that the scale of the infestation is so large that the five fly-killing machines he has installed are catching around 1,000 of the creatures a day.
Gary Ormondroyd, chief environmental health officer at the council, told the newspaper: "We have agreed to assist the EA by carrying out some investigatory sampling of the insects from the affected businesses for confirmation of source material."
Earlier this month, the environmental health team at the council offered a £100 reward to anyone who could help them catch fly tippers who have been dumping asbestos boards in Dalston.