Scientific name：Diaspis boisduvalii Signoret
Most of the them have a tendency to gather together, and the white waxy secretions on the body of the males mix with each other, resembling cotton wool. They tend to gather around clusters of pseudostems or where the leaves have creases, and then they will gradually spread to other parts of the plant. The affected leaves become yellow, and the central part of the yellow sometimes turns brown and the mesophyll appears hollow. The long-term damage causes the leaves to wither and the plant growth potential weakens. They also continuously secrete sweet-scented honeydew, which is the nutrient that ants like to feed on. Therefore, they often coexist with ants. In addition, it can induce mycoticosis, which makes the leaves covered with a layer of coal-like fungus that contains an awful appearance and affects the photosynthesis of the plants.
The female adults have a circular shell, yellowish in the center, white in the periphery and translucent. The male insects are white, with parallel strips on both sides, three distinct ridges on the back, white powdery waxy secretions covering the body, and adults have wings.
Scientific name：Chrysomphalus aonidum Linnaeus
The front and back sides of the leaves can be parasitized. A clear circle of yellow halo can often been seen on the green leaves, which indicates a larger-sized insects.
Female adults have shells about 2 mm in diameter, round, bulging from the dorsal side, with sharp central projections, which are reddish-brown/gray-brown/dark-brown bobbins. The outer shell is lightly colored. The male shell is smaller than the female shell and has an elongated shape with a diameter of about 1 mm. The insect body is orange yellow.
1. Do not purchase orchid seedlings with insects. Newly purchased orchids should be carefully inspected to ensure that no insects are on that, in case the insects are transmitted to other plants.
2. Always check the plants and note if there is a small amount of insects. Once it appears, wipe it off with wet cotton or a soft brush or spray soapy water to suppress its population.
3. Remove the old leaves that have been severely damaged.
4. Strengthen the greenhouse ventilation and the implementation of leaf irrigation. Doing so can reduce the occurrence of insects.
5. If the disease has occurred severely, the pesticide should be used to prevent it. The control of the insects from spreading is not easy, and a few surviving individuals can rapidly breed into a large group within a short time. Therefore, the pesticide should be applied continuously at least once a week or so, until they’re all gone.
6. For the more expensive orchids, it is advised to take preventive pesticides and spray insecticides on a regular basis.