How to control the Japanese wax scale on goldenrain tree? First understand its occurrence pattern

The Japanese wax scale (Ceroplastes japonicus Gr.) belongs to the order Homoptera, family Coccidae. Also known as the Japanese wax scale and the jujube armored wax scale, commonly called the jujube louse. When it breaks out over large areas on goldenrain trees, in severe cases the entire tree's branches and leaves are covered with the insects, and female insects attached to the twigs look like snow from a distance. The nymphs suck sap on the leaves, and their excrement covers the whole tree, weakening the tree's vigor and seriously affecting the landscaping appearance. Through two years of investigation and study, the occurrence pattern of this pest was clarified, and a satisfactory control method was found.

This pest has one generation per year, overwintering as mated adult females densely clustered on one- and two-year-old small twigs. Eggs are laid beneath the female body, and each female can lay 1500-2000 eggs. Overwintering adult females begin feeding in March and April, the body rapidly enlarges in mid- and late April, and egg laying begins in mid- and late May. The egg stage lasts 25-30 days, and nymphs begin to appear in late June. Newly hatched nymphs mostly rest quietly under the female's scale, and only disperse outward after several days, mostly crawling to the areas along both sides of the leaf veins to cause damage. After several days they secrete wax, form a scale, and become fixed in place. After the female matures, it migrates from the leaf back to the twig, mates with the male, and then fixes itself on the twig to overwinter. Male nymphs begin to pupate in early and mid-August, the pupal stage lasts about 15 days, and they emerge as adults in late August and early September. After the male and female mate, the male dies, and the female overwinters.

During the egg hatching period, if there is much rain, high air humidity and normal temperatures, the egg hatching rate and larval survival rate are both very high, reaching up to 100%, and the damage that year is severe. Conversely, if there is a lack of rain, high temperatures and dry conditions during this period, large numbers of eggs and newly hatched nymphs dry up and die under the mother's scale, and the damage that year is light. During the overwintering period of adult females, if there is more rain and snow and ice forms on the twigs, the natural mortality rate is high.

Control measures

1. Manual control: From November to March of the following year, overwintering adult females can be scraped off, and in combination with pruning, infested branches can be cut off.

2. Knocking off ice to eliminate overwintering adult females: In severe winter, if there is rain or snow and a thick layer of ice forms on the twigs, promptly strike the branches to shake off the ice, which can dislodge the overwintering insects along with the ice.

3. During the major outbreak period of nymphs, spray 40% omethoate + 40% isocarbophos at 1000-1500 times dilution, spraying 2-3 times at intervals of 7-10 days.

4. Carbofuran root irrigation: Use 25% wettable powder at 200-300 times dilution to irrigate the roots twice in May, which is very effective at killing nymphs.