You could buy $14 Katchy refill glue boards, or use packing tape
Having kids, I have pest problems. Sometimes it’s from food they left out somewhere and sometimes it’s just really random (fresh produce sometimes produces nasty.) Every year at least once the kitchen becomes a battle zone with fruit flies or Indian Moths because we dared purchase something fresh without a sippy straw and preservatives.
In this corner: The Katchy
As such, the Katchy gets broken out to handle the small pests. Now, might seem a little overkill but catch them early and without poison is my goal.
I got the Katchy a couple of years back for significantly less than it’s listing for on Amazon right now, picked up some glue boards because I thought I would need them. Placed the sealed glue boards underneath the unit so they would never be separated when I needed to replace them, and they were gone within a week, thrown into some junk drawer that nobody can find.
Problem when you live with people that think every drawer is a junk drawer.
In this corner: Transparent Packing Tape
Anyway, your options are from that point to not use the air and glue based fly trap, spend $8-14 for some replacement glue boards, or get yourself a $1.50 roll of clear packing tape ($2.60 on Amazon,) and make your own glue board. Works as well. Takes a couple of seconds to cut and place.
I personally cut about 5 inches, bend it over backwards, secure in the base of the Katchy. Repeat once. Small pieces of tape if I need to pull it down so it doesn’t connect with the exhaust.
You can also just cut a small strip and lay it down sticky side up if you want.
At about one to two cents a foot for tape, you’re doing yourself a solid if you investigate whether this will work for you. If it doesn’t work out for you, you’re out two cents of tape. It’s a little less than the $1.72 I’m seeing per pad at the moment.
Winner by decision: Tape
I don’t have a good metric of this, but the tape has historically worked fine. Your experience may vary, but even if it isn’t as sticky as the glue pads, once flies are in they’re going to get stuck on it eventually.