PEST 411
Tea scale
A major pest on hollies and camellias by Gurjit Singh and Shimat V. Joseph, UGA Department of Entomology
Lorraine Graney, Bartlett Tree Experts, Bugwood.org
Fig. 1. Brown-colored females (red arrow) and white-colored males (orange arrow) of tea scale.
Chazz Hesselein, Alabama Cooperative Extension System, Bugwood.org
UAC MAGAZINE | WINTER 2020
Fig. 2. Yellow spots on upper side of camellia leaves due to tea scale feeding underneath.
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Tea scale, Fiorinia theae (Hemiptera: Diaspididae) (Fig. 1) is a serious economic pest of camellias and hollies in nursery and landscape. Tea scale is an armored scale that causes chlorosis of the leaf tissues and under severe infestations, plants may die. The insects undergo multiple overlapping generations in a year and are very challenging to control. Even after the control measures are administered, the plant retains the damaged leaves for at least a season. It usually takes 2-3 years to bring the infestations under control after application of effective insecticides.
It is an invasive pest native to Asia and thought to be introduced into the US in early 1900s. Currently, it infests numerous plant species throughout the warmer regions of the world. In the US, its range varies from Florida, Georgia, South Carolina, and Louisiana in the southeast to Texas and California in the west. It mainly causes economic losses to camellias and hollies. In India, where it was first described, it has been reported on tea (Camellia sinensis), olives (Olea europaea), and citrus (Citrus sp.).
Identification and biology Growth and developmental rate of tea scale varies with the region's environmental conditions. This pest completes a life cycle in 45-65 days depending upon the temperature. In Florida, it is active throughout the year, but in the colder regions of Georgia and South Carolina fewer yearly generations are observed. An adult female tea scale lays two rows of 10-15 eggs under the scale covering, which hatch within two weeks. Tea scale undergoes three nymphal stages. The newly hatched scale nymphs, called crawlers, move from one plant to another by wind and crawling and spread the infestation. Within a week, these crawlers insert their piercing and sucking mouthparts into the succulent plant tissues underneath the leaf and become immobile. After 10 days, the crawlers molt into second nymphal stage. Thereafter, they lose all the appendages (legs and antennae) and remain immobile. Females (Fig. 1 [red arrows]) retain the skin from the first molt which becomes sclerotized over time and give the adult female its characteristic brown color. The adult females are 1/10th of an inch in length. The nymphal stages of males are initially yellow but as they grow, they secrete a thin soft white waxy shield (Fig. 1 [orange arrows]). Adult males develop a pair of wings, a pair of halteres and non-functional mouthparts. The adult males are usually smaller than the females.
Symptoms and damage The tea scales pierce the plant tissues underneath the leaves and suck the sap causing chlorosis or yellowing on the upper leaf surface (Fig. 2). Infested plants look unhealthy with fewer and smaller blooms. Under heavy infestations, white cottony filaments can be seen hanging from the leaves and the twigs dieback, sometimes causing death of the plant (Fig. 3). Dead scales and damaged leaves remain on the plant for a season or two, making the plant aesthetically unappealing to consumers.
