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Common Name:Rice seed midge Scientific name: Chironomus spp.
Adult midges resemble small mosquitoes. They swarm over rice fields, levees, and roadside ditches. Eggs are laid in strings on the surface of open water. After emerging, the larvae move to the soil surface, where they live in spaghetti-like tubes constructed from secreted silk, plant debris and algae. The larvae develop through four instars before pupating under water in tubes. The life cycle from egg to adult requires one to two weeks.
Damage caused by mite: Larvae injure rice by feeding on the embryo of germinating seeds or on the developing roots and seeds of very young seedlings. Injury from the midge can be insignificant to very severe. Injury can also be localized, making damage assessment difficult. In some instances, whole fields may need to be replanted. In other instances, only parts of fields may require reseeding. Midge injury is indicated by the presence of chewing marks on the seed, roots and shoots and by the presence of hollow seeds.
Facts: Larvae feed on the embryo of germinating seeds or the developing roots of young seedlings. Midge injury occurs in water-seeded rice and is usually not important once seedlings are several inches tall. Midge injury is indicated by the presence of chewing marks on the seed, roots and shoots and by the presence of hollow seeds. If midge injury is present and plant stand has been reduced to fewer than 15 plants per square foot, treatment may be necessary.
What should you look for: Rice seed midge is a problem only for rice seeds and seedlings in water-seeded fields. Fields should be scouted for midge injury 5-7 days after seeding. Check for hollow seeds and chewing marks on the seed, roots and shoots. Repeat scouting at 5- to 7-day intervals until rice seedlings are about 3 inches tall. Midges are not a problem in rice more than 2 to 4 inches tall. Midge presence is indicated by larval tubes on the soil surface. There are many midge species, most of which do not attack rice, and the presence of midge tubes alone does not indicate the need to treat a given field.
How you can manage rice seed midge: Drain fields to reduce numbers of midge larvae. Reseeding of heavily infested fields may be necessary. Avoid holding water in rice fields for more than two to three days before seeding to discourage the buildup of large midge numbers before seeding. Pre-sprout seed and avoid planting in cool weather to help to speed rice through the vulnerable stage and reduce the chance for serious damage.