Slender Rice Bug (Leptocorisa oratorius)

A Silent Rice Pest That Strikes at Dusk

During the most sensitive stages of rice development—such as panicle initiation, milk stage, and grain filling—farmers may encounter an inconspicuous but destructive pest: the Slender Rice Bug (Leptocorisa oratorius). Though slender and unassuming in appearance, this insect causes direct damage to rice yields and grain quality by piercing and sucking sap from developing grains.

Basic Information

• Common Name: Slender Rice Bug
• Scientific Name:Leptocorisa oratorius (Fabricius)
• Family: Alydidae
• Order: Hemiptera

Morphology & Biology

• Dorsal side: Brown
• Ventral side: Green

• Forewings: Hemelytra (hardened base, translucent tip)
• Hindwings: Membranous

• Agile and quick to fly when disturbed
• Emits a strong odor from abdominal scent glands
• Active from late afternoon to evening; rests on grasses during the day

Life Cycle (Incomplete Metamorphosis)

• Incubation: ~7 days
• Eggs laid in rows (10–12 eggs) along rice leaf midribs
• Reddish-brown, disc-shaped eggs

• Duration: ~18 days
• Five molts before adulthood
• Greenish-brown, often seen in groups

• Average lifespan: ~21 days

Complete life cycle: ~2–3 months

Feeding Behavior & Damage

Host Plants:

• Primarily grasses in the Poaceae family, especially rice

Damage Symptoms:

• Shriveled grains
• Lightweight kernels
• Overall reduction in grain quality and yield

Geographic Distribution

Widespread in rice-growing countries including:

• Australia
• India
• China
• Indonesia
• Philippines
• Thailand
• Myanmar
• Bangladesh
• Malaysia
• Papua New Guinea
• Samoa
• Parts of Central America

Integrated Pest Management (IPM) Strategies

To control L. oratorius effectively, implement the following practices:

✅  Weed Control

• Remove weeds in and around rice fields to reduce hiding and breeding sites

✅ Sweep Netting

• Use sweep nets to capture and remove nymphs and adults

✅ Use Bait Traps

• Hang decaying meat in fields to attract and trap adults, which are drawn to protein sources

✅ Avoid Continuous Cropping

• Break pest life cycles by avoiding back-to-back rice cultivation

✅ Use Insecticides with Caution

• Apply Carbosulfan (Pos 20% EC) at 80 mL per 20 liters of water
• Recommended when pest density exceeds 4 bugs per square meter during the milk stage

✅ Conclusion

The Slender Rice Bug (Leptocorisa oratorius) is a serious pest of rice during its most vulnerable reproductive stages. Though thin and inconspicuous, its piercing-sucking feeding method can lead to widespread reductions in yield and grain quality. Early detection, timely field inspections, and integrated pest management strategies are crucial to preventing long-term infestations and sustaining crop health.