Control Fungus Gnats | | | It's not the adult flys but the larvae in the soil that are both the problem and the focus of control measures. | | Nematodes are widely used to control fungus gnats. They are easy to apply through the irrigation system. However, they do not reproduce well within the small host larvae and pupa and repeated applications are necessary to maintain control. Because it is not possible to create a reproducing population of nematodes it is best to use larger numbers of nematodes than commonly recommended by suppliers. In addition, like all biologicals, there may be quality differences between batches and/or suppliers. We found that the lower numbers recommended did not always show significant gnat population reductions (2002, 2003, 2004, 2005) and thus increased quantities up to 10 times the recommended dose. These larger numbers are available at minimal cost from suppliers who specialize in nematodes. The most effective and commonly used nematode species is Steinernema feltiae. | Nematodes, rove beetles, and predaceous soil mites attack the fly larvae and pupae. A type of Bacillus thruingiensis that is specific to flys is also effective (Bacillus thuringiensis israelensis). Adult fungus gnats live only about a week and their populations quickly drop when larvae and pupae are destroyed.
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