Go to the drain area and squash as many of the drain flies as possible with a standard fly swatter. While destroying the breeding grounds will prevent the flies from laying more eggs, you'll still have to deal with adult drain flies up to 20 days after you clean the drains. As such, you may want to take extra measures to get rid of as many as possible. If a fly swatter is inefficient, treat the infested area with an insect spray that works in confined spaces.  Close all the doors and windows in the space. Spray the insect poison upward for 5 to 8 seconds per 1000 cubic feet (305 cubic meters). Leave the treated area and keep it closed for 15 minutes or more. Open all windows and doors after returning to the area. Run an electric fan, if possible, to help disperse any remaining spray. Reapply as often as once every week.

How would you rephrase that briefly using Chinese?
使用苍蝇拍杀灭大苍蝇。 使用空间喷雾。