Controlling cluster flies can be extremely difficult

Q. My 5-year-old country home has windows fitted with triple-track storm windows and screens. In late summer and fall we are besieged with flies. How can we get rid of these pests?

Mrs. Ruth T. Cirba Bolton, Binghamton, N.Y.

A. We fired off this question to George W. Rambo at the National Pest Control Association in Dunn Loring, Va. Here is his reply:

''The writer of the enclosed letter is experiencing problems with cluster flies. These small flies, resembling house flies, move inside around cracks and crevices in the building in late summer. They do not reproduce inside, but hibernate.

''When the days get warmer, or even on sunny days in the winter, the hibernating flies become active, fly to windows, then die.

''It is extremely difficult to close off the small openings the flies find to enter the buildings. Recent research has shown that a pesticide application to the outside of the building is needed. This application has to be done at the critical time when the flies are entering the house.

''I would suggest your inquirer contact a few pest-control operators in New York to solve the problem.''