Tea Scale Pests on Camellias
Camellia – sometimes called the rose of winter. Just outside the living room window at the homeplace grew an enormous red blooming camellia. As we drove up the road that approached the house, it welcomed us home, so it’s no surprise that Camellia plants mean home to me. Today there are over 200 different species of Camellia and the number of named camellia varieties is believed to be as high as 20,000, and increasing. Three species of camellia are in general cultivation as landscape ornamental plants: Camellia japonica, C. sasanqua, and C. reticulata. Varieties of these species bloom in red, pink, or white, or in combinations of these colors. Although the blooms are not spectacular, our southern summers would not be the same without the most popular camellia – the Camellia sinsensis, also known as the tea plant.
Which brings us to one tough pest that plagues camellias, some holly plants, and a few other hosts. The scale insects, in particular the tea scale. Scale insects appear very different from many other types of insects. They are usually quite small and have sucking mouthpieces with which to feed on plant juices. There is the Camellia scale, which infests only the leaves and the armor of the female scales resembles a tiny oyster shell. The Peony scale which appear as white circles or small brown humps on the bark and can kill twigs and branches, and the Tea Scale.
As the weather warms up get prepared to scout for this pest. They are most common on interior leaves. Recognize this pest from the yellow splotches on the surface of the leaves that result from the feeding insects grouped on the leaf undersides. Adult female tea scales are about 1/10 inch long and are covered with a hard brown cover. The males produce white waxes that cover their bodies. In heavy infestations, these white waxes make the underside of the leaf appear cottony. This insect can impact the vigor of the entire plant and may interfere with the blooms.
Timing is key to controlling scale insects, and understanding the lifecycle of the pest is essential in taking effective action. Each female deposits from 10 to 15 eggs under the scale shell. They hatch in 7 to 21 days, depending on the weather. The flat, yellow crawlers migrate to the newer growth on the plant and, in 2 or 3 days, attach themselves. The life cycle is usually completed in 60 to 70 days. Because there are many overlapping broods, crawlers can hatch continuously from March to November.
If just a few leaves have scales, as indicated by yellow spots, picking these leaves off could prevent an outbreak and any further treatment. For larger, established infestations more aggressive intervention will be required. Horticultural oil is recommended for homeowners. Horticultural oil is effective at killing crawlers as long as it hits them so coverage is important. Repeat applications will be necessary to kill new crawlers that emerge from adults that survive. Using broad-spectrum insecticides such as pyrethroids or organophosphates actually kill off the natural enemies of scale insects, so the scale populations increase. Systemic products are available that provide longer control and are softer on the beneficials that prey on killing scale insects. Note that an insecticide application will never kill every individual of a pest population. It is the job of natural enemies to clean up after and between insecticide applications.
To learn more about these pests and how to control them, read Pests of Camellia.
Minda Daughtry is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.