What are the control methods for the black scale insect on flowers?

The black scale insect, also known as the coffee black scale, has many host plants. On flowers it mainly damages sago palms, spiderworts, coral trees, crotons, Swiss cheese plants, spider plants, camellias, citrus, palms, oranges, pomelos and so on.

Adults and nymphs suck the host's sap on the leaves and branches of flowers. In mild cases the leaves turn yellow, and in severe cases the leaves dry up and fall off, and the honeydew they secrete easily causes sooty mold.

It produces 3 generations a year. The first generation of newly hatched nymphs appears in late May, the second generation of newly hatched nymphs appears in August, and the third generation appears in early November. Female adults lay their eggs under the helmet-shaped scale, each female laying about 300 eggs, often reproducing by parthenogenesis, and the female adult dies right after laying eggs.

Control methods:

(1) Manually prune off infested leaves and branches, or scrape and brush the insects off the leaves and branches, taking care not to knock off tender branches and buds.

(2) Spray 2.5% deltamethrin and other pyrethroid pesticides at a 2000-3000 times dilution during the peak hatching period of the nymphs.