What are the control methods for the Chinese parasol tree psyllid?

The Chinese parasol tree (Firmiana simplex) is one of the main urban landscaping tree species in northern China, with a tall, straight trunk, attractive leaf shape, and good shading effect. However, the Chinese parasol tree psyllid causes serious damage, greatly affecting its ornamental effect. After long-term observation, garden workers have gradually worked out the occurrence and development patterns of the Chinese parasol tree psyllid, carried out effective control, and accumulated certain experience, which is introduced below for reference.

I. Damage characteristics and symptoms

The Chinese parasol tree psyllid, also known as the Chinese parasol tree split-head psyllid, belongs to the order Homoptera, family Psyllidae. It uses nymphs and adults to suck sap on Chinese parasol tree leaves or young twigs and tender trunks, with young trees suffering the greatest damage. The white cotton-like waxy substance secreted by the nymphs blocks the stomata on the leaf surface, affecting normal photosynthesis and respiration of the leaves, causing the leaf surface to show symptoms of pallor and shrinkage. The secretion contains sugar and often induces mold parasitism; when the damage is severe, the leaves fall early, the twigs dry up, and the epidermis becomes rough and brittle, making it susceptible to wind breakage.

II. Morphological characteristics

The female adult is yellow-green, with a body length of 4 to 5 mm and a wingspan of about 13 mm; the compound eyes are dark reddish-brown; the antennae are filiform and yellow, with the last two segments black. The egg is slightly spindle-shaped, slightly pointed at one end, about 0.7 mm long, yellow-white or yellow-brown when first laid, turning light reddish-brown before hatching. The final-instar nymph is slightly cylindrical in body shape, covered with a relatively thick white waxy substance, grayish-white overall with a slight green tinge, with a body length of 3.4 to 4.9 mm.

III. Life history and habits

In the Weifang area of Shandong, this insect has 2 generations per year, overwintering as eggs; the overwintering eggs begin to hatch in late April and early May of the following year. The nymph stage lasts more than 30 days. Eclosion begins in early to mid-June, with the peak of eclosion in late June. The second-generation nymphs hatch in mid-July and eclose in early to mid-August. In late August, the second-generation eggs begin to hatch. The occurrence period of this insect is extremely uneven, and various different insect stages can be found at the same time.

Both adults and nymphs of this insect are gregarious, often gathering in groups of a dozen to several dozen on tender shoots or branches and leaves, mainly on tender shoots and the undersides of leaves. During the nymph stage, the insects all cluster within the waxy flocculent substance; this insect moves quickly and has no jumping ability. After eclosion, adults always crawl and rarely fly; if disturbed, they use jumping to assist flight. The jumping distance can reach more than 33 cm. Their flying ability is weak, and they rarely fly more than 2 m. After eclosion, adults need about 10 days of supplementary nutrition before mating and laying eggs. Mating mostly occurs before 8:00 and around 19:00. Egg laying begins 2 to 3 days after mating. Eggs are laid on the shaded side of the main branches near the trunk, on the undersides of leaves, or where the leaf stalks are attached, but the egg-laying positions of the first- and second-generation adults differ: the first generation mainly lays eggs on the undersides of leaves, while the second generation lays them on the twigs. The eggs are laid singly; each female can lay about 50 eggs, and the egg stage lasts 10 to 12 days. The adult lifespan is about 42 days.

IV. Control methods

1. During the damage period, spray clean water to wash off the flocculent substance, which can kill many nymphs and adults.

2. Spray a 1000-fold dilution of 40% omethoate emulsifiable concentrate to control adults and nymphs.

3. During the early nymph stage or during a major outbreak, use a 1:15 dilution of 40% monocrotophos solution for trunk injection, which is extremely effective for control.