General Information

Common name: Rice stem borer
Lepidoptera:Pyralidae

Host plants

Yellow stem borer feeds only on rice plants, while other species feed on barley, sorghum, maize, wheat, and grasses

Distribution

White stem borer is found in Indonesia, Philippines, Malaysia, and Australia. Yellow stem borer is common in Southeast Asia, China, India, and Afghanistan. Striped stem borer is present in India, Southeast Asia, China, Iran, and Southern Europe. Dark-headed borer is an important pest in Malaysia and Thailand. Pink stem borer is present in the India, China, and Southeast Asia.

Damage

All rice stem borer species cause the same crop injury and damage to rice plants.

1. Stem borer larvae cause deadhearts and whiteheads. Deadhearts are the dried- up central shoots of tillers while whiteheads are the discolored panicles with empty or partially filled grains. These visible symptoms vary at the plant growth stages at which infestation begins. Seedlings and tillers attack at the base of the stem have deadhearts. An attack on the bearing panicles usually produces whiteheads.
2. Transparent or yellowing leaf sheaths. The damaged leaf sheaths have transparent patches that sooner turn yellowish-brown and eventually become dry.
3. Presence of entrance or exit holes on the stem. Stem borers eat through the node and bore down the stem. They leave the stem above the node and enter in either another tiller, or at the neighboring inter-node of the same stem.
4. Larvae feed on the tissues around the node causing the stem to break.
5. The signs are the tiny holes on the stems and tillers. Fecal matters are found inside the damaged stems.

Description

Rice stem borer species

1. Dark-headed stem borer (Chilo polychysus)
   The egg is flat, scale-like and is not covered with hairs. The freshly deposited egg mass is white and is found near the base of the leaves and leaf sheaths. Larvae are grayish-white in color, have five longitudinal stripes of grayish-violet or purplish-brown and with large black heads. The adults are brownish-yellow in color.


2. Gold-fringed stem borer (C. auricilius)
   The fresh eggs of the gold-fringed stem borer are white. They are scale-like in appearance. With age, they turn pale yellow to brown. When ready to hatch, the eggs turn blackish. The larva has a black head and five pinkish longitudinal stripes, which run the entire length of the body. The adult moth is straw-colored to light-brown with silvery specks on the discal cell of the forewings.


3. Pink stem borer, Violet stem borer (Sesamia inferens)
   The egg of the pink stem borer is nearly spherical or bead-like in appearance and laid in rows between the leaf sheath and the stem. A freshly laid egg is creamy white and is not covered with hairs. After a day, it turns light yellow. With age, it turns pink and black. Newly hatched larvae are white with a yellowish tinge and black head capsules. Mature larvae turn pinkish purple with brown or orange-red head capsules. A larva measures 2.5 to 3.5 cm long and 3 mm wide. The adult is robust and is tan-colored with dark-brown markings. A purplish-red band radiates from the central point in the forewing to the wing tip. The pink stem borer belongs to a family different from the other stem borers. It is related to cutworm and armyworm.


4. Striped stem borer (C. suppressalis)
   The eggs of the striped stem borer are disc-shaped. Newly laid eggs are white. With age, they turn yellow and then black when they are ready to hatch. A larva has a large head, which is shiny brown or orange in color. Its body color is light brown or pink with five rows of longitudinal stripes that run the entire length of the body. The adults are brownish yellow with silvery scales and a row of 7 or 8 small black dots at the terminal margin of each forewing. The forewings are darker than the hind wings.


5. White stem borer (Scirpophaga innotata)
   The eggs are similar to those of the yellow stem borer. The larva of white stem borer is whitish to light yellow in color. A fully-grown larva is 2.5 cm long. The larva has no body marks. Adults are similar to the yellow stem borer in appearance but are immaculately white in color. They have a group of long hair on the thorax.


6. Yellow stem borer (S. incertulas)
   Eggs are white in color; they are oval, flattened, and covered with brownish anal hairs of the female moth. The larva has a pale hairless yellow body with a small orange head. The female is whitish to yellowish in color. It has a pair of clear black spots in the middle of each forewing. The male is smaller and is dull in color. It has two rows of black spots at the tip of the forewings.