Thrips numbers outside are lowest in winter. If possible, roses and nursery stock should have no leaves at the time of planting. You can look out for western flower thrips on your property and your crops by frequent close inspection of your plants. In addition, you can use sticky traps. The best traps for monitoring thrips are blue because they catch few other insects.
Yellow traps catch many kinds of insects and it is often difficult to recognise the thrips.
Note that blue traps will catch other kinds of thrips. Traps can be hung near openings or just above the tops o the crop plants. Western flower thrips is most active in the region of flowers and young growths. Also, follow all of the recommendations in the previous section because thrips are difficult to control. A key to living with western flower thrips is to keep populations low outside the greenhouse so that only a few are around to get onto the new crop.