I've been waging war on gnats since last fall. Oh, it started, as best I recall, in September. When..for no reason I can think of, I found some fungus gnats on a potted basil plant in a window. I kind of shrugged it off. It was getting towards the end of the season and while I've wintered my herbs in the window they've never done very well.
But last fall they did especially poorly and I gave up on them. Finally ripped out all my herbs (except my rosemary - they don't seem to have any interest in rosemary) and let the pots dry out. I figured that would be all it would take. The pots were left bone dry all winter long and I figured for sure. No gnats would survive. I hadn't seen a single gnat in months.
I got started in spring with basil, thyme, oregano and cilantro.
And several weeks later...to my horror...I had
clouds of gnats!
I tried
everything. I tried killing them with a diluted alcohol and mild soap solution. It burned the leaves. I tried yellow
sticky traps. I tried the vinegar soap traps (that work so well for fruit flies). I tried watering with diluted hydrogen peroxide. That destroyed the roots of my herbs to the extent they weren't really good for anything.
Nothing worked.
I decided I'd just start all over. But rather than start over
completely I'd bake my (clay) pots of soil in the oven to sterilize them and then start with seeds and new plants. This seemed to work...but ...not so fast! I'd left behind a couple of cilantro plants I thought were untouched. Only to find ...several weeks later...gnats in my cilantro! I dumped all the cilantro and just
hoped hey hadn't spread.
But...no! I found...two gnats on my basil!
Which brings me to the purpose of my post. Sometimes...I'm smarter than I look! I don't want to start over again this late in the season. And I just
love my fresh herbs in all kinds of ways. So. I took some cheesecloth...
And I cut up Kleenex sized pieces and tucked them all around the soil at the stems of my basil. Looking at it after I'll bet cotton balls will work too.
The logic here being...if (any) adults can't reach the soil they can't lay eggs (they can each lay 200 eggs!). And further, if the larvae can't escape the soil there will be no more adults. So. An adult trying to reach the soil will get trapped in the cheesecloth. And any larvae trying to escape the soil will...get trapped in the cheesecloth.
Hopefully this works and I'll start over again next spring.