Rice leafminer

Hydrellia griseola

The rice leafmineradult is a small, olive-green fly (0.018 inch long) commonly found in the early-season walking on the water surface or on rice leaves lying on the water surface. The females lay their elongate, white eggs singly on the upper surface of these leaves. They prefer leavesfloating on the water, and high humidity (80–100% relative humidity) is required for hatching. In 3 to 5 days, eggs hatch into cream-colored, maggot-shaped larvae. The larvae burrow between the outside leaf layers and mine the leaf. Larvae may pupate in an existing mine or migrate to a different leaf to form a new mine. Total development time from egg to adult is about 2 weeks at 85° to 90°F. Rice leafminers generally overwinter as adult flies, and they may begin to lay eggs on leaves of a wide range of grasses associated with aquatic habitats as early as February.

Damage
Injury is caused by leafminerlarvae feeding in mines between the two epidermal layers of a leaf. The mines usually contain a swelling, which is the body of the feeding or pupating leafminer. Themined area on the leaf fades to a light green color at first, then turns yellow and may appear white with time if it dries. Because high humidity is required for hatching, leafminer infestationsare usually confined to leaves lying on the water surface. The larvae are mobile and move on to new leaves after old ones are completely mined. In severe infestations, they may also mine the leaf sheath.

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