While talking with a friend about indoor plants recently, we got on the topic of pests. “What are those little black flies that buzz around my face when I’m working on the computer?” she blurted. “They drive me crazy!”
I had to chuckle. I’ve written a weekly garden column for over 20 years and believe me, I never lack for material…
You might’ve experienced them, too. They buzz around your face when you’re eating dinner or, like my friend, when you’re working on the computer. It’s irritating, like dogs that bark late at night or finding an empty toilet paper roll at an inopportune time.
These itty-bitty flies are called fungus gnats. They’re the size of sesame seeds and they eat eat like pigs. (I’ll explain shortly).
‘Fungus gnat’ is not a pretty name, but it fits, because they live and graze, quite contentedly, in the soil of indoor plants.
The flying insects, the critters you’re most likely to meet, are the adult and final stage of a 3-week life cycle. Are you ready for a little biology?
Let’s start at the larval–little worm–stage, which takes place in the soil where they chomp on root hairs and decaying organic material. Don’t lose sleep over fungus gnats, though. They are more of a nuisance than trouble. But if left alone to breed to their hearts’ content, they can kill a plant.
If you suspect that fungus gnats have set up camp in your plants, here are three solutions:
1. Be a pest
Two can play this game. The object is make life uncomfortable for the little guys by allowing the soil dry out between waterings. Fungus gnats thrive on damp, decaying matter, so a parched desert-type environment is not where they want to raise a family.
2. Make a spray
Sprays are effective against all kinds of pests, including aphids, thrips, and fungus gnats.
Soap and water spray
You can buy commercial sprays, such as Safer products, or you can mix your own. Here’s how: Add one tablespoon of liquid soap to two quarts of water. Use a soap that’s a pure soap such as Dr. Bronner’s, rather than one that contains chemical additives. Hand and body soaps generally tend to be safer for plants.
Essential oil spray
To a quart of water, add 1/2 tablespoon of peppermint oil, cedar wood oil and/or neem oil (also known as tea tree oil or melaleuca) and 1/3 teaspoon liquid soap (Dr. Bronner’s), which also works as an emulsifier.
Fill a spray bottle with a spray recipe of your choice and spritz the soil and the inside edge of the container or pot. Spraying the plant itself is not as critical because unlike aphids that tap into the soft tissues of leaves and stems, fungus gnats take flight (often when disturbed) and tip toe in and around the soil.
3. Sticky traps
Sticky traps are my favorite anti-gnat solution. They’re just a card, usually yellow, that’s coated with a sticky goo. You can buy sticky traps or make your own. It’s easy. Here’s how:
Color is the bait, and pests prefer yellow. The source of the yellow color is not important. So long as it’s bright yellow, it can be made of:
- Paper card stock
- Flexible cutting boards
- Plastic or paper file folders or plates
- Painted wood
The base material: For indoors or in greenhouses and other protected garden areas, paper or card stock may be OK for one-time use traps. For outdoors though, make your traps sturdier. Maybe coating a rubber ducky would work? Thing is, with a little bright yellow paint, pretty much anything will do, from plastic milk jugs to aluminum cans inverted on a stick.
The sticky goo: If you can’t find commercial sticky coating such as Tanglefoot, again, you have options. Simply apply a layer of petroleum jelly or a thin coating of motor oil to the base surface. The oil isn’t as sticky, but it’s sticky enough to capture pests. Just remember, sticky traps also capture beneficial insects, so check on them frequently).
After positioning your traps, in a few hours, you can start counting the casualties. Though I highly recommend removing the sticky trap from sight if you have guests coming over for dinner.
As for things that irritate you, I remember reading a story about a young man who was sitting in a circle with other students, listening to their guru-teacher discuss how to be “in this world, but not of this world.” As the night drew on, so did the mosquitoes. Soon all the students were waving their arms, swatting at the intruders.
“Why are you fidgeting so?” their teacher said sternly. “Is the whole world going to change for you? Change yourself: Be rid of the mosquito consciousness.”
Whoa, Nellie. Now there’s an interesting way to get rid of pests.