Are scale insects harmful to humans? Explained clearly in one article

Scale insects are an important group of pests on citrus and pomelo trees. Common ones include the red scale, brown scale, cottony cushion scale, arrowhead scale and cottony cushion scale, among others. Some species are important pests, damaging leaves, twigs and fruit, causing leaves to turn yellow, twigs to wither, tree vigor to decline, and easily inducing sooty mold. Let us take a look below at whether scale insects are harmful to humans!

Are scale insects harmful to humans?

Scale insects are not very harmful to humans. Scale insects mainly harm plants. After the female adult lays eggs, within a few days they hatch into movable small insects without a waxy scale covering. The larvae crawl on ornamental plants, and after finding a suitable spot, they pierce their mouthparts into the plant body, suck the sap, and begin a fixed life, causing the host plant to lose nutrients and lose a large amount of water. After young buds and tender twigs are damaged, growth is poor and they often turn yellow and wither. While harming ornamental plants, some also excrete large amounts of honeydew, which leads to sooty mold, preventing leaves from carrying out photosynthesis. Severely affected plants decline in vigor and eventually the whole plant dies.

Host plants of scale insects

Scale insects are extremely widely distributed, with the majority in tropical and subtropical regions. Their relationship with host plants is fairly complex. Most scale insects are polyphagous, able to feed on many plant groups. For example, the cottony cushion scale has more than 100 host plants, among which it most prefers Australian wattle, citrus and beefwood. Some scale insects are monophagous, and some species in certain families or genera are specialized and can only parasitize a fixed plant group, such as species of the genus Fiorinia, which parasitize only bamboos, and the pine oyster shell scale, which parasitizes only pine trees.

Control techniques for scale insects

1. Plant quarantine: Scale insects are often firmly attached and parasitic, with tiny bodies, and mainly spread over long distances by being carried on host branches, scions, fruit and even trunks. Quarantine should be implemented during the purchase, transport and protected areas of seedlings, scions and fruit to prevent spread and proliferation.

2. Agricultural control: Strengthen orchard management, timely cultivate and loosen the soil, fertilize and irrigate, meet the water and fertilizer needs of fruit trees, which can enhance tree vigor and improve the trees' insect resistance. Combined with shaping and pruning, burn the insect-bearing branches in a centralized manner, which can greatly reduce the pest population.

3. Biological control: The natural enemies of scale insects in nature include pathogenic microorganisms and insects, among which the latter are the most important. Moreover, various places have successful experience in protecting and utilizing natural enemies to control scale insect damage, which should be summarized and promoted.

4. Physical control: Seizing the 2 weak links in the life activities of scale insects and using physical and mechanical methods can achieve twice the result with half the effort. For the giant mealybug, the method of digging pits near the tree roots can also be used to eliminate it under the tree.

5. Chemical control: Use a combination of three agents: methidathion, thiamethoxam and an organosilicon penetrant. When applying, spray the leaves and wet the soil surface or drench the roots to kill the eggs in the soil. The dilution ratio is 1:1500. Take 1 gram of each agent, totaling 3 grams.