12-3-2020 KERALA, INDIA - RICE GRASSHOPPER (Genus Oxya)

The genus Oxya, commonly known as rice grasshoppers or rice-field grasshoppers, belongs to the family Acrididae (subfamily Oxyinae). These insects are significant agricultural pests in Asia and Africa, primarily known for causing damage to rice, sugarcane, and maize crops. They are well-adapted to marshy environments, often found in or near wetlands and agricultural fields. 

Here are key facts about the genus Oxya:

1. Appearance and Biology

Physical Characteristics: Oxya species are generally small to medium-sized grasshoppers. They are typically pale green to yellow-brown in color, often featuring a distinct, dark-brown, longitudinal stripe on either side of the head and pronotum.

Adaptations: They are well-adapted to wet, marshy conditions, with hind tibiae and tarsi that are flattened, functioning like oars to allow them to swim.

Life Cycle: They undergo incomplete metamorphosis (egg, nymph, adult).

Eggs are laid in the soil, usually in egg pods (often 25–40 eggs per pod) that are covered with a protective froth, enabling them to withstand harsh conditions.

Life Span: In many regions, they have one or two generations per year, with the egg stage often lasting through the winter (up to 200–300 days). 

2. Habitat and Ecology

Habitat: They prefer moist, humid environments, specifically rice fields, grasslands, and marshes.

Distribution: Highly widespread throughout Asia, particularly in Indomalaya and eastern Asia (e.g., China, Japan, Pakistan, India).

Diet: Oxya species are polyphagous, feeding on a variety of plants, but they mainly feed on rice, maize, millet, and other grasses. 

3. Pest Status and Damage

Feeding Behavior: Both nymphs and adults are highly destructive. They chew large angular holes in leaves, which can lead to complete defoliation, leaving only the leaf mid-ribs.

Crop Impact: They can cause severe yield losses, particularly by damaging tender leaves, stems, and filling panicles (grains). 2–4 adults per square meter can reduce rice output by 6.8–17.8%.

Management: Natural enemies include spiders, birds, and various parasitic larvae.