Brown Bugs on My Orchids

Tea scales are brown insects found on the undersides of orchid leaves.

Orchids provide a splash of color to any yard or garden. This flower comes in a variety of colors that grows well with the proper care. Orchids, however, are susceptible to insect infestations that affect the health and vigor of the plant. The tea scale is a common orchid pest that injures the plant by feeding on it. As a result of tea scale infestations, orchids can suffer from reduced vigor.

Identification

Orchids are susceptible to tea scale infestations. This scale insect has a hard shell on its back, which is known as armor. Adult female tea scales begin with flat, yellow colored armor that turns hard and brown, and males have white, soft armor. Tea scale nymphs are flat, yellow and have six legs for crawling. Female tea scales deposit eggs under their armor, which hatch in seven to 21 days. Tea scales typically live for 60 to 70 days.

Types

While orchids are a favored host of tea scales, other plants and flowers are infested as well. The Chinese holly, Japanese holly, mango, tea plant, Satsuma orange, ferns, dogwood, yaupon and bottlebrush are all commonly attacked by the brown tea scale.

Effects

Tea scales are most often found feeding on the undersides of orchid leaves. Upper leaf surfaces often develop yellow blotches from feeding injuries and the leaves may drop from the plant prematurely. Orchids infested with tea scales do not produce as many blooms as orchids without insect infestations. The presence of scale insects often causes the orchid to gradually decline, reducing the vigor and beauty of the flower. Scale insects secrete a sticky substance, which is known as honeydew. This substance sticks to the leaves of the orchid, causing a condition known as sooty mold to develop. Orchids with sooty mold develop a black coating of velvety fungus, which can become quite unsightly.

Control

Light infestations of tea scales often are effectively controlled by placing a cotton ball in alcohol and wiping the insects from orchid leaves. Predatory insects feed on scale insects, keeping them low in number. Lacewigs, lady beetles and parasitic wasps all feed on scales. Heavy tea scale infestations usually require chemical control methods. Homeowners are encouraged to use horticultural oils for scale control on orchids. Using insecticidal sprays may not be an effective means of scale control because it can kill predatory insects that feed on scales. If insecticides fail to penetrate the scale's armor, it can result in a decrease in predatory insects and cause an increase in scale populations.

References

• MOBOT: Kemper Center Factsheet: Orchids: Problems
• NCSU: Tea Scale: Steven D. Frank, S. Bambara