A possible weapon against leaf miners and fungus gnats

Over the years, I’ve written about my battles with leaf miners, which are the larvae that tunnel in between the cells in the leaves of spinach, beets and Swiss chard. How do they get there in the first place?

Well, the adult is a fly that lays eggs on the leaves. Once the eggs hatch, the maggots do their damage to the leaves. Very annoying! And let me tell you, they can damage a whole bed of the above crops very quickly. My solution has been to place floating row cover over the beds of these crops and leave the cover in place for the entire season. It works really well.

However, I recently received an email from a reader, asking what to do about the leaf miner adults that still manage to sneak in under the floating row cover and lay their eggs. I rarely have this happen but it’s still a possibility. I did mention to the reader about the importance of weighting down the edges of the row cover with bricks, rocks or boards.

Now bear with me, while I take this discussion a bit further…

About 2 weeks ago, I discovered that there were a lot of fungus gnats in my little greenhouse. I’m sure they have hatched out of the potting soil that I planted my seedlings in, but it’s really annoying.

Fortunately, I’ve found something organic that is supposed to work on both fungus gnats and leaf miner adults, along with white flies, aphids and thrips. Interested? (aha, now I have your attention!)

It turns out that Gardens Alive! sells a product called Pot Stickers. That’s what you’re looking at in the photo above. It’s a butterfly-shaped cut-out made from sturdy yellow paper that is coated with a sticky substance.

The flies are attracted to that color, land on it and become, shall we say, permanently stuck. I decided to try it out in my greenhouse so I hung it between a couple of small bamboo stakes. As you can see (at left), it’s working its magic… on both sides, I might add. It’s primarily for use indoors although can be used outdoors as well.

So where do leaf miners come into play? Well, I’m still going to put row covers over my spinach, beets and Swiss chard beds, but I’m also going to carefully place a couple of Pot Stickers under the row cover in the hopes of catching any sneaky leaf miner adults that manage to get in under the covers. It’s worth a try.

One thing I like about this product is that it uses a “special glue that won’t stick to fingers” and actually, while you’re putting it in place, it’s covered with peel-off covers that you don’t remove till the last minute so nothing will stick to it until you have it in place. Nice!

The Pot Stickers don’t contain any pesticides so it’s completely organic. I purchased a pack of 10 Pot Sticker traps for $9.95, so they are a buck apiece.

Here is a link to information on fungus gnats from the University of California, if you are curious about them.