Question
I have a peace lily in a pot that is approximately 12" x 12" x 12". I bought it and repotted it in May 2006. It has been healthy. It gets some sunlight in a relatively low humidity environment. I moved in September so the plant traveled in a truck approximately 7 miles. The plant has been doing well and just got a new flower. Tonight, when pruning the plant, I noticed that there were little white "worm" looking bugs in the soil. They have have legs and heads and don't move. I've noticed a lot of gnats recently in my apartment. I think they may be an early stage of the gnats. The tips of all of the leaves were brown even though the rest of the leaves are green and thriving. Do you know what the bugs may be? How can I get rid of them? Should this help to take care of the gnat problem?

Thank you!

Answer
Hi Renee,

Yes, it is likely that the critters you see in the soil are fungus gnat larvae. Here's what you need to know:

Adult fungus gnats fly around and are an annoyance, but they are not harmful to people. Each gnat lives for about 5 days. The trick is to get rid of the next generation - the gnat larvae that live in the top layer of the soil. The larvae feed on decaying organic matter. Decaying pine bark in potting mixes and decaying plants roots feed the larvae.

Try to keep the soil as dry as possible. Remove all loose soil from the surface and put a light layer of coarse coir (coconut husk) or sand or diatomaceous earth on the soil surface. These substances have sharp edges that carve up the larvae. (Recent studies indicate that fine-textured peat moss also deters gnat larvae.)

Another safe technique is to place ?inch slices of raw potato on the surface of the soil. After a day or so, discard the slices along with the larvae inside. Repeat this until there are no more larvae in the potato.

For more serious infestations try Knock-Out Gnats to treat fungus gnats available from Gardens Alive for about $20. See http://www.gardensalive.com/item_display.asp?ProductNumber=1962

Detection trick: Add a little water to the soil and then look very closely for tiny fungus gnat larvae swimming in the water as it pools on the surface. You need good light and good eyes to see them. If you don't, then your plant is probably gnat free.

Prevention is often the best remedy. Use sterile potting mixes that are free of bark chips. The potting mix should have ample drainage material, such as perlite so that it drains well and allows the soil to dry out frequently. Fungus gnats can nearly always be traced back to overwatering and/or poor soil quality.

To attract and capture the adult flying gnats, pour a little red wine into a small glass (cooking wine will work, if you don't want to waste the good stuff!) and leave it out for the day. Repeat the treatment as necessary.

The brown leaf tips are unrelated to the fungus gnats. Check your water quality. If it is on the hard side, switch to filtered or distilled water.

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

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