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Tea Garden Pest Control: Managing Tea Geometrids

Tea, as an indispensable part of our daily lives, its growing environment—the tea garden—is also filled with rich ecological diversity. However, this ecological diversity sometimes brings about some problems. In tea gardens, various pests can sometimes become a major challenge we face.

These pests not only threaten the yield and quality of tea leaves but may also cause damage to the entire ecological environment of the tea garden. Therefore, understanding these pests and mastering control methods is a crucial task for us agricultural workers.

In the Tea Garden Pest Control Series column, we will introduce you to the types, habits, modes of damage, and control methods of these tea garden pests. We hope that through our popular science efforts, you can have a deeper understanding of tea garden pests, thereby better protecting our tea gardens and allowing every tea leaf to grow in the best environment. The first article in this series is the common tea geometrid.

Identification of Tea Geometrids

Tea geometrids are a type of moth in the Lepidoptera family Geometridae, also known as Geometrids, Inchworms, Twig Inchworms, or Loopers. Tea geometrids mainly damage the leaves of tea trees and are one of the main pests of tea trees in China. The morphological characteristics, habits, and occurrence patterns of tea geometrids are as follows:

Adult Stage: Adults are 9-12mm in length, with a wingspan of 20-30mm, with males being smaller. The wings are sparsely covered with black-brown scales, with three wavy lines and seven small black dots on the forewings, and two transverse lines and five small black dots on the hindwings. They are phototropic, active at night, and rest with their wings spread flat during the day within the tea bushes.

Larval Stage: Larvae are 26-30mm in length, cylindrical in shape, with a brown head. The body color is light brown or light gray-brown, with a grayish-black rhomboid spot on the dorsal surface of the 2nd to 4th abdominal segments, and an inverted "eight" shaped spot with small protrusions on the dorsal surface of the 8th abdominal segment. Larvae avoid sunlight and hide on the undersides of leaves or in shady areas of tea bushes during sunny days, and they may hang down and produce silk when disturbed.

Pupal Stage: Pupae are 10-14mm in length, elongated oval in shape, with males being smaller. They are reddish-brown, with a darker head. Antennae and wing buds reach the 4th abdominal segment, with a pair of eye-like spots on each side of the front edge of the 5th abdominal segment, and the anal spines are nearly triangular, with male pupae having a short bifurcated spine at the tip. Pupae are found in the soil near the base of tea trees, where they overwinter for more than 5 months.

Egg Stage: Eggs are 1mm in length, oval in shape. They are initially green, later turning gray-brown, and black before hatching. They are usually laid in clusters of tens to over a hundred, covered with white fluffy material. Eggs are laid in crevices of tea tree branches, soil cracks, fallen leaves on the soil surface, or among branches and leaves.

The damage symptoms of tea geometrids manifest as leaves being chewed into arc-shaped notches. In severe cases, leaves and tender shoots may be completely eaten, affecting not only the yield of tea leaves for the current year but also causing the decline of tree vigor, resulting in reduced tea production for the next year. The characteristic of tea geometrid damage is that it occurs in multiple generations, reproduces quickly, spreads rapidly, and is prone to outbreaks. Serious infestations occur in tea-producing provinces south of the Yangtze River, especially in provinces such as Jiangsu, Zhejiang, Anhui, and Hunan.

Control Methods of Tea Geometrids

Given the occurrence characteristics and degree of damage of tea geometrids, the following control methods can be adopted:

Deep Plowing to Destroy Pupae: Deep plowing in the inter-row spaces of tea gardens to unearth overwintering pupae and expose them to sunlight, causing their death and reducing the source of insects.

Manual Trapping and Killing: Utilize the phototactic behavior of tea geometrids to lure and kill them with light or use unmated females to lure and kill males, reducing the number of mating and egg-laying.

Chemical Control: During the peak period of tea geometrid occurrence, select low-toxic, high-efficiency, and safe pesticides for spraying, such as flubendiamide, tebufenozide, and chlorfenapyr, spraying once every 7-10 days for 2-3 consecutive times, paying attention to prevent pesticide damage and residues.

Biological Control: Utilize natural enemies of tea geometrids, such as the nucleopolyhedrovirus of tea geometrids, to produce viral insecticides, infecting tea geometrids and causing their death, achieving the purpose of control.

Yeehar Agricultural Science has been deeply engaged in the field of green prevention and control for many years and has developed a series of products including natural enemy-friendly series, insect situation monitoring and forecasting series, and trapping series, aiming to achieve the goal of "disaster prevention and reduction, quality improvement and efficiency increase, and safety guarantee". We have various methods for trapping and controlling tea geometrids.

1. Multi-functional Flying Insect Traps: Using sex lure technology to attract tea geometrids, followed by killing them with a high-voltage grid. Powered by solar energy and lithium batteries, with long battery life and easy installation, it can effectively control the number of tea geometrids in the area.

2. Insect Situation Monitoring and Forecasting Device: Based on comprehensive technologies such as electronics and information technology, Yeehar Agricultural Science has developed a counting-type monitoring and forecasting device, equipped with specific lures developed by the Tea Research Institute of the Chinese Academy of Agricultural Sciences to attract tea geometrids. This product has the characteristics of strong targeting, small size, high cost-effectiveness, and high accuracy.

3. Boat-shaped Sex Pheromones Traps: Sex pheromone technology is the first line of defense in the current green control of tea tree pests and is an important alternative and supplementary measure to chemical pesticides. Among various types of traps, boat-shaped traps have good capturing effects on tea geometrids and are ideal companions for sex pheromone lures.

Notes on the Prevention and Control of Tea Geometrids

When conducting the prevention and control of tea geometrids, attention should also be paid to the following:

Timing of Control: Control measures should be implemented based on the occurrence pattern of tea geometrids, focusing on the initial outbreak period and peak occurrence period, especially for the overwintering generation and the first generation. Timely control should be exercised to prevent their spread and proliferation.

Control Methods: Various control methods should be comprehensively utilized, including physical, biological, and agricultural non-chemical control measures. Additionally, appropriate use of chemical pesticides should be considered, aiming to avoid the development of resistance in tea geometrids and minimize any negative impacts on tea trees and leaves caused by a singular method.

Effectiveness of Control: Regular monitoring and evaluation of the occurrence and effectiveness of control measures for tea geometrids are necessary. Based on actual circumstances, adjustments should be made to control measures to ensure the health of tea gardens and the quality of tea leaves.

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