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Identification Methods and Control Techniques for Tea Geometrid Moths

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Geometrid moths, commonly known as inchworms, are insects of the order Lepidoptera, family Geometridae. There are many species of geometrid moths in tea gardens, mainly the tung tree geometrid, the silver geometrid, the grey geometrid and the camellia geometrid, among which the tung tree geometrid occurs most frequently. The tung tree geometrid, also called the large geometrid, is the largest geometrid species occurring in tea gardens. Its larvae cause damage, with a large appetite and many host plants; in severe cases they eat all the buds and leaves of the tea garden, leaving bare stems. The adult of this insect is silvery grey, with a body length of 20-25 mm and a wingspan of 50-70 mm. The wing surface is densely covered with small black dots, the forewings have 3 relatively distinct yellow

Geometrid moths, commonly known as inchworms, are insects of the order Lepidoptera, family Geometridae. There are many species of geometrid moths in tea gardens, mainly the tung tree geometrid, the silver geometrid, the grey geometrid and the camellia geometrid, among which the tung tree geometrid occurs most frequently. The tung tree geometrid, also called the large geometrid, is the largest geometrid species occurring in tea gardens. Its larvae cause damage, with a large appetite and many host plants; in severe cases they eat all the buds and leaves of the tea garden, leaving bare stems. The adult of this insect is silvery grey, with a body length of 20-25 mm and a wingspan of 50-70 mm. The wing surface is densely covered with small black dots, the forewings have 3 relatively distinct yellow-brown wavy lines, and the hindwings have 2 wavy lines. The female moth has a stout abdomen with a tuft of yellow hairs at the tip. The larvae vary greatly in colour, changing with the habitat; grown larvae reach a body length of 70 mm, with a depression in the centre of the head, a pair of raised spots on the back of each of abdominal segments 4 and 5, and a pair of horn-like projections on the head of the pupa. The eggs are oval, 0.7-0.8 mm long, bright green when newly laid, later turning pale green, covered with yellow hairs. The adults of this insect like to rest during the day on tall trees near the tea garden or on utility poles or buildings below 1 zhang, and the larvae greatly increase their food intake from the 4th instar onward, possessing protective coloration and mimicry.

The following methods can be used to control the large geometrid:

1. Biological control. Use polyhedrosis virus preparations (such as Aolü No. 1) or Bacillus thuringiensis preparations (BT).

2. Catch and beat adults. Focus on April, the peak emergence period of the overwintering generation of adults, and organise catching and beating in the early morning.

3. Eliminate pupae. In conjunction with tillage, management and fertilisation, use a small-toothed rake to collect the pupae or bury them deep in the soil.

4. Spraying for control. Control agents can be selected from Tianwangxing, Dülü, Kung Fu, Nongdile, etc.

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