The crown net bug of rhododendron

Also known as pear net bug, pear net bug, flower belongs to Hemiptera, Pentatomidae. All over the country. With nymphs, adults harm rhododendron, rose, camellia, Michelia, jasmine, wax plum, wisteria and other potted flowers and trees.

For the harmful adults and nymphs are clustered on the back of the leaves to suck juice, and the back of the injured leaves looks like a black sticky substance that has been splashed. This feature can be easily distinguished from other piercing pests. The whole injured leaf is yellowish yellow on the back, and many pale spots are formed on the front, and when the damage is serious, the spots become patches, so that the whole leaf is green, and a pale leaf is seen from afar, falling leaves ahead of time, no longer forming flower buds.

Morphological characteristics the adult is about 3.5 mm long, flattened and dark brown. Antennae filiform, 4-segmented. The central protuberance of the anterior chest dorsal plate is longitudinally raised, extending backward into a leaf-like process, and protruding outward on both sides of the forechest into a pinna. The forewings are slightly rectangular. There are very consistent reticular striations on the front wing, the forechest and the leafy process on the back. When still, the front wings are folded and look squarely at the whole insect body from top to bottom, like an "X" shape composed of many wings.

The egg is oval, curved at one end, ca. 0.6 mm, light green at birth, translucent, and then yellowish.

The nymph is milky white at first hatching, and then it gradually turns dark brown, about 1.9 mm long. At the 3rd instar, the wing buds were obvious and looked like adults, and there were obvious conical spines on both sides of the 3-8 segments of the forechest, middle chest and abdomen.

The annual generation of life history and habits occurs in 4-5 generations in the Yangtze River Basin and 3-4 generations in North China. Adults survive the winter in withered branches, fallen leaves, weeds, bark cracks and soil and stone crevices. In the first and middle of April, the overwintering adults began to move and concentrated on the back of the leaves to feed and lay eggs. The egg is laid in the leaf tissue, with a yellowish-brown gel on it, and the egg period is about half a month. Most of the newly hatched nymphs are harmful on both sides of the main vein. The nymph broke off for 5 times and became an adult after about half a month. The first generation of adults occurred at the beginning of June, and the later generations were in July, early August, late August and early September respectively. Because of the long adult period, long spawning period and overlapping generations, all insect states often exist at the same time. The damage was the most serious from July to August, the population density was the highest in September, and overwintered one after another after late October. Adults like to be active at noon, and the number of eggs laid by each female varies from host to host, ranging from tens to hundreds of eggs, with a constant to dozens of adjacent eggs, and there is a small black spot with a slight depression in the center outside the spawning site.

Control methods: thoroughly remove the fallen leaves and weeds around the potted flowers and bonsai gardens in winter. Chemical control of plants with thicker and rougher stems should be coated with white coating. It is the most favorable time for chemical control from the stinging activity of overwintering adults to the hatching of the first generation nymphs. Spray 50% fenitrothion 1000 times, or 40% omethoate 1000-1500 times, or 10-20% pyrethroids 1000-2000 times, once every 10-15 days, 2-3 times continuously.