Rice leafminer maggot half-way pulled out of a rice leaf. Rice leafminers are so named because they "mine" the interior of the leaf, causing the plant tissue to die. Photo by J. Saichuk, LSU AgCenter.

Rice leafminer maggot in leaf. Note the bump. This is where the maggot is mining the inside of the leaf. To scout for rice leafminers, run your thumb and forefinger over the leaves and feel for these bumps. Photo by J. Saichuk, LSU AgCenter.

Brown structure is a rice leafminer pupa cut out of the leaf. This photo also shows the dieback that results from leafminer maggots mining the leaf interior. Photo by J. Saichuk, LSU AgCenter.

Overview:

Adults are metallic blue-green to gray flies with clear wings (1/4-inch long). They fly near the water and lay eggs on rice seedling leaves. Transparent or cream-colored larvae emerge in less than one week and feed between the layers of the rice leaf. Larvae become yellow to light green while feeding for one to two weeks before pupation. Adults emerge and live two to four months. The life cycle is completed in two weeks to one month.

Facts:

• Leafminers attack rice fields in early spring in the same vicinity year after year.
• Infestations usually occur where water is deepest on the upper side of levees.
• Leafminers are not usually a problem in shallow water.
• Leafminers are more severe in continuously flooded than in periodically flooded rice.
• Larvae tunnel between the leaf layers (mining the interior), attacking and killing leaves closest to the water before moving up the plant, killing additional leaves and possibly the entire seedling.

What you should look for:

• Walk through flooded rice fields and draw leaves between your thumb and forefinger.
• Bumps in leaves indicate leafminer larvae or pupae.

How you should manage rice leafminer:

• Maintain water depth at 4-6 inches.
• Lower the water level in fields so that rice leaves can stand up out of the water.
• Treat if plant numbers are reduced to less than 15 per square foot.