Oligonychus ununguis, commonly known as the chestnut red spider or chestnut leaf mite, is a pest that affects chestnut trees. It causes visible damage to the leaves, starting with small greenish-yellow spots that gradually turn brown and necrotic in severe cases. The mites tend to congregate along the edges of the main veins on the upper side of the leaves, and they often leave behind thin strands of webbing. In more advanced infestations, you may also find small numbers of cockroaches and eggs on the underside of the leaves. Adult females are oval-shaped, about 0.5 mm in size, and slightly reddish-brown in color. Males have a diamond-shaped body, and their eggs are round, dark red at the top, with a white silk thread on top. Summer eggs are yellow, while winter eggs are brown or greenish-brown after feeding. Young nymphs hatch from both winter and summer eggs, appearing milky white initially, then turning brown or green after feeding. They have three pairs of legs when young, and four pairs when they become adults. The chestnut red spider has 4 to 9 generations per year. Overwintering eggs are laid on the back of branches, bark crevices, and twigs. These eggs hatch between late April and early May, with peak activity occurring in mid-May to early June. Newly hatched nymphs climb to the base of new shoots and feed as the shoots grow. The first generation of adults appears in mid-May, and by mid-October, females can lay up to 40–70 eggs per day. Each generation overlaps, leading to heavy infestations during the third to fifth generations, typically from June to July. The period when chestnut leaves are fully developed is the most critical time for control. After early September, the population begins to decline as winter eggs start to form. Summer eggs are mainly found on the main veins of the leaves, while winter eggs are located on the branches. The mites are easily removed by wind and rain, and infestations are more common in dense plantings and on sunny slopes. Dry and hot weather conditions lead to earlier and more severe outbreaks. Natural predators include black ladybugs, red star ladybugs, lacewings, and parasitic wasps. To manage Oligonychus ununguis, it's important to take preventive measures. During winter, prune affected branches, remove rough bark, and scrape the trunk area to eliminate overwintering eggs and adults. From late March to early April, apply a 3-degree lime sulfur solution to young saplings and grafted trees. In early May, treat the tree trunks by cutting a 5–10 cm wide ring, scraping off the rough bark, and applying insecticides such as 50% Dimethoate EC, 40% Omethoate ECG, or 20% monocrotophos. Apply the insecticide, let it dry, and repeat if necessary. Then cover the treated area with mulch, plastic film, or waste paper to enhance effectiveness. From late May to late June, acaricides can be sprayed regularly to control the mite population effectively. Consistent monitoring and timely intervention are essential to prevent severe damage and maintain healthy chestnut trees. N2 Cylinder,N2 Gas Cylinder,N2 Gas Tank,Nitrogen Gas Cylinder JIANGSU NEW FIRE FIGHTING TECHNOLOGY CO.,LTD , https://www.newayfire.com