The Hawthorn leafhopper, also known as the Hawthorn red spider, is a pest belonging to the order Acarina and the family of leafhoppers. It is commonly found in pear and apple-growing regions across China, where it infests fruit trees such as pears, apples, peaches, and mountain plants.
This pest feeds by sucking the sap from buds, leaves, and fruits. Initially, it causes small chlorotic spots on the leaves, which gradually expand into larger patches. As the infestation progresses, the leaves turn pale brown, and the undersides become covered with webbing and knots. This damage can lead to early leaf drop, weaken secondary growth, and reduce flowering and fruiting.
Female adults have two forms: winter and summer types. The winter type measures 0.4–0.6 mm in length and appears bright red and shiny. The summer type is slightly larger, ranging from 0.5–0.7 mm, with a purple or brown coloration. A black spot is present on each side of the body, and the legs are light yellow.
Juveniles have three pairs of legs and appear roundish, yellow, or white. After feeding, their eggs take on a pale green color, with dark green spots appearing on both sides. When they reach the fourth instar, they become light green, fully developed, with yellowish highlights, bristles on the back, and dark green markings along the sides.
The eggs are oval-shaped, ranging in color from yellowish to orange-yellow, and turn reddish before hatching.
In terms of life cycle and habits, the Hawthorn leafhopper completes 5 to 9 generations per year in northern fruit-growing areas. All stages of the insect, including fertilized females, cluster in cracks and soil near the base of trees, especially around swollen buds. Activity begins when the average daily temperature reaches 9–10°C.
During the pear harvest period, the population peaks, and after leaves unfurl, the pests move to the underside of leaves. They tend to concentrate on branches near the main trunk during this time, with egg-laying peaking just before or during apple bloom. Eggs hatch within 8–10 days, and adults emerge simultaneously. Overlapping generations occur after the second generation. In early May, the population remains low, but it increases exponentially in June, reaching its peak in July. The spatial distribution follows an accumulation pattern, starting with dense populations in the inner canopy and spreading throughout the tree later.
By early August, increased rainfall and natural predators help control the population, leading to a decline in numbers by September. At this stage, the insects begin preparing for winter, with females developing into overwintering forms.
Control methods include trapping and killing overwintering females on the trunk before the season starts. During dormancy, scraping old bark, especially on main branches, is effective. Combining this with sprays of lime sulfur or a 3–5% oil-based diesel emulsion, particularly after scraping, can enhance control.
During the growing season, chemical treatments are recommended during the egg-laying and hatching periods. Options include spraying 20% tetracycline (e.g., Deuterated Net, Apollo) at 2000–3000 times dilution, or 5% Nissoline at 1000–1500 times. Other options include 1.8% Qi Qi Su (Avermectin) at 4000–6000 times, 15% Broom Net at 2000 times, and 73% Kekeite at 2500–3000 times. These agents should be alternated to prevent resistance.
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