Most common pests are mealy bug and scale . Both can be controlled by broad-spectrum insecticides recommended for use on orchids.
Mites can be a problem during hot weather.
Since these tiny pests are hard to see, look for irregular rust-colored pitted areas predominantly on the underside of leaves. Use insecticides that are specifically recommended for controlling mites, since most broad-spectrum insecticides are ineffective. Poor air circulation and wet conditions on cool nights encourage fungal and bacterial diseases . You can prevent most problems by avoiding overcrowding and by watering early in the morning to allow the plants to dry by nightfall. A few dry brown leaves are not cause for alarm.