Issue 10, June 27, 2011

Fungus Gnat Maggots

Several areas of the United States are reporting large numbers of fungus gnat maggots crawling across turf and sidewalks. These insects in the Family Sciaridae feed on decaying organic matter in the soil. When full grown, they are about 3/8 inch long, slender, wormlike, and clear with black head capsules. They are coming up onto the surface where they migrate to pupate. These masses are reported as being round and 2 to 6 inches across, or more commonly as masses up to 2 inches wide and several inches long.

Fungus gnat larvae are more likely to be numerous in areas with an overabundance of water from rainfall or irrigation. Over-watering newly laid sod can result in large populations of these larvae eating young roots. Reducing irrigation will cause a reduction in the number of fungus gnat larvae and allow the sod to root.

These larvae are not likely to cause any damage to established turf and can be ignored or washed away with heavy streams of water. As adults, they are known as dark-winged fungus gnats, which are frequently very common in the spring and fall in Illinois, flying as large swarms up to several feet across. (Phil Nixon)

Phil Nixon

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