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Economic importance: Parasitoid.
Hosts: Stem borer eggs and pupae.
1. Tetrastichus schoenobii is a metallic blue-green or shining green with bluish luster insect. It has an 8-segmented brown antenna except for the yellow scape.
2. The hairs clothing the wings are not in rows. The thorax is smooth and shining and the abdomen is elongated and pointed.
3. The legs are yellow except for the greenish coxae I and III. The tarsi are 4-segmented in all the legs.
Biology and ecology
1. Tetrastichus schoenobii parasitizes stem borer eggs and pupae. Several wasps may parasitize an egg mass of stem borers. Before oviposition, the female examines the egg mass for where to probe through the hair mat.
2. Each female parasitoid lays one egg in each stem borer egg. It can produce 10 to 60 offspring. Egg incubation takes 1 to 2 days. Larval development takes place inside the egg host.
3. Once the egg is consumed, the larval parasite moves out from the egg and locates another egg host for its development. Each larval parasite needs three eggs for its development. Adulthood is observed after 1 to 2 days.
4. This parasitoid is common in wetland and dryland rice fields.