Getting Rid of Fungus Gnats
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Just when I’ve been feeling good about not having fruit flies around the house because I’ve been using a wasp jar trap, I’ve suddenly begun seeing little flying bugs again. On close scrutiny I’ve found they are not fruit flies, with their enchanting red eyes. No, these are fungus gnats, which don’t have red eyes, though they do look like another pest. A small non-biting mosquito. Seems I brought the gnats into the house with a bunch of garden herbs I’m over-wintering inside.

Fruit fly traps don’t work for fungus gnats because they’re a bug with a different set of habits altogether. Not into beer or wine, fungus gnats like, instead, damp, humus-rich soil, where they lay their eggs. When the eggs hatch, small burrowing larvae roam the pot looking for rich organic matter. In the process, they often eat the plant’s roots, causing a lot of damage. Plant symptoms of infestations include, sudden wilting, loss of vigor, poor growth, yellowing, and foliage loss.

When it comes to life cycle, The Ohio State University Fact Sheet on Fungus Gnats says:

Adults live about 7 to 10 days and deposit eggs on the moist soil surface or in soil cracks. Females lay up to 100 to 300 eggs in batches of 2 to 30 each in decaying organic matter. Eggs hatch in 4 to 6 days; larvae feed for 12 to 14 days. The pupal stage is about 5 to 6 days. There are many overlapping generations throughout the year.

Prolific and frustrating, these naughty gnats can be quite difficult to get rid of. Not only do they infest and harm your plants, they infest your house, as well. So what’s a green person to do? First off, forget the poisonous insecticides. There are better ways to handle the situation.

Prevention is the first step. The Ohio State University recommends:

• Before buying or bringing garden plants into the house, check them for gnats. (Though sometime this isn’t so easy to do.) If infested, don’t bring them in.
• When repotting plants, use sterile potting soil.
• Don’t over water.
• Let the soil dry out as much as possible before watering. This can kill many of the larvae.

Natural treatment methods include:
• Throw out your plants. An extreme but effective method.
• Use the sticky yellow traps all around your plants, such as Safer’s Stick Strips Trap. They help trap and kill whitefly, thrips, aphids, fungus gnats, and many other insect pests, so they don’t get a chance to breed.
• To get to the root of the problem, one of the best methods is to use a bacterium called Bacillus Thuringiensis Berliner var. israelensis.

So just how do bacteria kill fungus gnat larvae? The Extension Toxicology Network says that:

B.t. [Bacillus thuringiensis] forms asexual reproductive cells, called spores, which enable it to survive in adverse conditions. During the process of spore formation, B.t. also produces unique crystalline bodies. When eaten, the spores and crystals of B.t. act as poisons in the target insects. B.t. is therefore referred to as a stomach poison. B.t. crystals dissolve in the intestine of susceptible insect larvae. They paralyze the cells in the gut, interfering with normal digestion and triggering the insect to stop feeding on host plants. B.t. spores can then invade other insect tissue, multiplying in the insect's blood, until the insect dies. Death can occur within a few hours to a few weeks of B.t. application, depending on the insect species and the amount of B.t. ingested.
Not the prettiest way to go that’s for sure, but quite effective. B.t. is non-toxic to people, pets, and plants. Studies show it does seem to have negative effects on shrimp and mussels, though not to fish. And I should mention, it’s deadly to mosquito larvae, which is one of the main reasons this product was developed in the first place. It’s also important to note that the B.t. you use on caterpillars, is not the same kind you use on fungus gnats. They are different bacterial strains.

The biggest problem with B.t. is that it can be quite difficult to find in Canada. It took me awhile, but after an extensive online search, I found a Canadian company called Natural Insect Control (NIC) that sells the Bacillus Thuringiensis Berliner var. israelensis strain. The B.t. brand name they carry is called Aquabac Natural Mosquito Control. In the States, just look for Mosquito Dunks, click on the dunks above. Or Gnatrol, click on the bottle to the right.

When the Aquabac arrives, I’ll follow directions of product per gallon of water, then will water all of my plants with the solution, repeating in seven days, to give gnats in egg state a chance to hatch and have a munch. Then, I’ll play it by ear.

Until then, I eagerly await my bacteria, as I live amongst a horde of fungus gnats. Oh, how I miss those fruit flies. So easy to knock off with a little ole wasp jar and some nice apple cider vinegar.

Update Note: Aquabac works beautifully. It can take a couple of weeks before you’ re not seeing little flying things around anymore, but work it does.

Bulk organic herbs, spices and essential oils. Sin

Photo Credit: Brandon Blinkenberg

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