Occurrence and control of common scale insects (control methods of scale insect harm)

Scale insects have many kinds, similar habits and fast spread, and are important pests of many plants. Scale

Occurrence and control of common scale insects (control methods of scale insect harm)

Scale insects have many kinds, similar habits and fast spread, and are important pests of many plants. Scale insects are parasitic on branches, bud axils, twigs and leaves of plants, and are generally inactive or motionless. Female adults and nymphs suck the juice to get nutrition and water, which leads to weak trees and early defoliation.

First, the grass is walking. Also known as straw sandals scale insects and persimmon naked scale insects. It mainly harms many kinds of fruit trees such as peaches, persimmons, pears and apples, and garden ornamental plants such as cherry blossoms, magnolia grandiflora, wintersweet, rose, rose and Sophora japonica.

1, morphological characteristics. The female adult has an oval body, with a length of 8 8- 10/0mm and a width of 4-5mm. Her back is grayish purple in the center and pale yellow in the periphery, which looks like straw sandals. Her back is covered with fine hair and white wax powder. Nymphs are similar in appearance and reddish brown.

2. Regularity of occurrence. L generation occurs every year, and eggs overwinter in piles in soil cracks, bark cracks, litter layers and stones near roots. Nymphs began to appear in late February of the following year, and more trees were planted in early and middle March. After climbing the tree, nymphs concentrate on L-2 annual branches to suck juice, which is the most harmful in April. Severely damaged branches delay germination or even die. In the middle and late May, the female adult dives into the gap of the root to lay eggs, dies after laying eggs, and overwinters with eggs. Young nymphs have the habit of climbing trees at sunrise and getting off trees in the afternoon. If it's bigger, it won't get under the tree.

3. Prevention methods. (1) Taking advantage of the habit of young nymphs going up and down trees every day, a mound with a height of about 33 cm was cultivated at the base of the trunk in early March, and fine sand was sprinkled on it, and a small ditch was dug at the periphery to prevent nymphs from going up trees and killing nymphs falling into the ditch every day. Coat the trunk with waste heavy engine oil with the width of 10-20 cm (add a proper amount of contact killer such as fenpropathrin emulsifiable concentrate), and remove nymphs under the oil belt in time. Every lO-l5 days, 1 time, * * * 2-3 times. ⑵ Spray wine with 0.3 degree sulfur mixed solution, or 50% dichlorvos EC 1000 times solution, or 800 times solution of 40% dimethoate EC, and add 0. 1% washing powder. (3) When adults lay eggs under trees in summer, they pile some clods or litter at the roots to lure them to lay eggs and concentrate on killing them.

Second, the Japanese tortoise wax scale. Its host range is wide, mainly including ornamental plants such as Lagerstroemia indica, Magnolia grandiflora, Osmanthus fragrans, oleander, rose and peony, as well as various fruit trees such as peach, plum, jujube, loquat, apricot, hawthorn, apple, pear and fig.

1, morphological characteristics. The wax shell of female adults is oblate and oval, white, 3-4.5 mm long, and the back is concave like a tortoise shell. The living worms are light brown to purplish red, and the nymphs are light reddish brown when they are first hatched. After 1 day, wax began to secrete, and wax shell was formed after 7 7- 10/day.

2. Regularity of occurrence. Generation L occurs every year, and fertilized female adults overwinter on branches or leaves of trees. In March and April of the following year, sooty blotch was often induced by resuming activities, sucking tree sap and discharging honey dew. During the wheat harvest, eggs are laid under the mother shell, and they hatch in late June. Nymphs crawl around to find suitable parasitic parts for fixation, mostly in leaves, and a few in petioles or twigs. If there is too much rain during spawning and hatching, the survival rate will be high, otherwise the mortality rate will be high. Newly hatched nymphs can generally crawl about 80 cm, and long-distance transmission mainly depends on wind diffusion. From late August to late September, male and female insects mate. After fertilization, the female insects continue to do harm, moving from leaves to branches to prepare for overwintering.

3. Prevention methods. (1) Cut off the branches with insects and clean up the fallen leaves in winter, and destroy them in a centralized way, or scrape off the overwintering insects on the branches, or spray 5- 10% light diesel oil emulsion and Pomei 3-5 degree sulfur mixture. ⑵ If the nymph does not secrete wax or wax is initially formed at the initial stage of hatching, spray it for control. You can choose 50% malathion EC 800- 1000 times or 20% pyrethroid EC 1000- 1500 times. ⑶ For tall trees, trunk spraying and injection can be used for prevention and control. Trunk application: in April, lightly scrape that bark at the base of the trunk (it is advisable to just expose the new bark) to form two semi-circles, the width of which is slightly equal to half of that of the trunk, and apply water-absorbing medicine for 400-500 times, then wrap it tightly with polyethylene film, and release it after l5-2O days. Trunk injection: inject the trunk from three directions according to the circumferential angle of l2O degree, and use 0.2g (active ingredient) per cm of trunk, and seal it with mud after injection. Choose internal drugs.

Third, brown soft scales. Orchids, evergreen trees, Milan, cyclamen, bamboo, jasmine, calla lily, cycads and other l7O plants.

1, morphological characteristics. Female adults often parasitize on the opposite side of vein. The body is oval, 2-4 mm long, and its color changes greatly, often yellow-green, yellow-brown or reddish-brown. There is a longitudinal ridge in the center of the back, and the periphery of the ridge is dark brown, and black spots are often scattered or integrated into patches, forming two brown reticular horizontal bands.

2. Regularity of occurrence. The annual generation varies from place to place, reaching 3- 18 generations, which occurs all the year round in the greenhouse. Overwintering with fertilized female adults or L-2 instar nymphs.

3. Prevention methods. Lighter potted flowers can be painted by hand, focusing on both sides of the midrib of the leaf back. The heavier ones are buried with l5% triamcinolone acetonide or 3% carbofuran granules, and the pots with a pot diameter of l7 cm are buried with triamcinolone acetonide or 2 g carbofuran along the pot edge.

Fourth, coccidia. Including a variety of coccidiosis, such as peach coccidiosis and apricot coccidiosis, mainly occurring on fruit trees and green plants, such as peaches, apricots, cherries, plums, Fraxinus mandshurica, willows, Amorpha fruticosa and purple leaves.

1, morphological characteristics. This scale insect is mainly parasitic on the branches of plants. Female adults are nearly spherical or spherical, and their body color is yellowish brown, reddish brown and so on. It is easy to identify.

2. Regularity of occurrence. Most species have L-2 generations every year, and most of them overwinter in the shade of branches. After germination in the next spring, they move to the tender branches to fix the sucking hazard. May is the time when adults lay eggs and nymphs hatch intensively.

3. Prevention methods. Use the Japanese tortoise scale.