Morphological Characteristics, Damage Symptoms and Control Techniques of Corn Thrips

Thrips are pests of corn at the seedling stage, mainly including the corn yellow thrips, the grass thrips and the rice tube thrips, small in size (0.9-1.3 mm), able to fly and good at jumping.So what do corn thrips look like? What do the damage symptoms look like? What control techniques are there?

What do corn thrips look like?

Adult corn thrips are divided into long-winged, semi-long-winged and short-winged forms. The body is small, dark yellow, with dark gray spots on the thorax. The forewings are grayish yellow, long and narrow, with few but prominent veins and long marginal hairs. The wings of the semi-long-winged form reach only the fifth abdominal segment, while the wings of the short-winged form are slightly bud-shaped, like an elongated triangle. The eggs are kidney-shaped, milky white to milky yellow. The nymph body color is milky blue or milky yellow, and the body surface is wrinkled with transverse rows of raised granules. The pupa or prepupa (that is, the third-instar nymph) is pale yellow, with wing buds that are pale white, and the pupal mass turns brown when emerging.

What do the damage symptoms of corn thrips look like?

1. Corn thrips mainly feed on leaf sap with the rasping-sucking mouthparts of adults and nymphs, and secrete toxins that inhibit corn growth. In recent years, due to drought and changes in farming systems, especially the diversification of corn sowing dates, the occurrence and damage of thrips have shown an upward trend year by year, and they have become one of the main pests of corn at the seedling stage. However, because thrips are small and their active damage sites are hidden, they are not easy to find, and it is easy to miss the appropriate control period, resulting in severe damage in the field.

2. Damage symptoms: Corn thrips are small pests of the order Thysanoptera and are one of the main pests of corn at the seedling stage. When damaging corn, the yellow thrips first damage the back of the leaves; the grass thrips and rice tube thrips first damage the front of the leaves. Both can cause the leaves to show intermittent silvery-white stripes, accompanied by small dirty spots. Severely damaged leaves often look as if they are coated with a layer of silver powder. Corn thrips mostly gather on the young leaves and the heart leaf of corn. After the corn leaves are damaged, pale spots appear. In severe cases, the distal half of the leaves wither and the heart leaf cannot emerge; even if it emerges, in some plants the heart leaf grows twisted afterward and the leaves cannot unfold, causing the leaves to grow abnormally in a "cow tail" shape, mostly forming a rosette-like tufted top or causing large numbers of dead seedlings, and even requiring replanting.

What control techniques are there for corn thrips?

1. In combination with field thinning, pull out infested seedlings and carry them out of the field for destruction, reducing the pest source and preventing its spread.

2. Apply more seedling fertilizer, water in a timely manner, increase field humidity, inhibit the growth and development of thrips, promote early and rapid growth of corn, and create an environment unfavorable for the occurrence and development of thrips so as to reduce damage.

3. Apply pesticides in time for control when the rate of infested corn plants in the field reaches 5% or the number of thrips reaches 30 per 100 plants. Commonly used chemical agents: 3% acetamiprid emulsifiable concentrate at 2000 times dilution, 40% chlorpyrifos emulsifiable concentrate at 1500 times dilution, 10% imidacloprid wettable powder at 1500 times dilution, 4.5% beta-cypermethrin at 1000 times dilution.