Orchid plants kept outdoors during summer months are inspected before being brought indoors for winter. Check the upper and under sides of leaves and flowers for visible bugs and insect eggs. A strong jet of water kills or dislodges many insects. Repot plants with an extreme bug infestation. Sticky honeydew substance indicates aphids. Black sooty fungus feeds on aphid honeydew.
Nontoxic bug spray for orchid insect pests is made from a mixture of 70-percent isopropyl (rubbing) alcohol and several drops of mild liquid soap. Excessive soap may cause leaf burn. Use in a hand-held or small-pump sprayer to kill mealy bugs, aphids, mites and scale. Alcohol dissolves the insect's waxy coating. They do not develop a resistance to alcohol. Orchids may also be immersed in a bucket of water overnight to dislodge ants, roaches, sow bugs and grasshoppers.
Horticultural-oil bug spray is made from mineral, vegetable or neem seed oil. It is also known as dormant oil or summer oil. Insect breathing pores are clogged and the oil interferes with their metabolic function. Horticultural oils are considered safe for organic growing practices. Apply weekly to reduce the population of aphids, scale, mites, mealybugs, sow bugs, caterpillars and pill bugs.
Compost tea is an effective fertilizer spray for orchids. It is easily made with one handful of compost soaked overnight in a gallon of water. Stir the mixture once and allow the bulk material to settle to the bottom of the container. Use the tea mixture in a hand-held spray bottle one time per week. Compost tea contains the 16 essential nutrients orchids need to grow and thrive.