If you're new around here, I live in a swamp. I know I'm supposed to call it a "pristine wetland," but if you don't mind, I'll call it the bog-to-hell-and-gone instead. Everything comes out of that swamp all the time, sometimes to delight us, sometimes to bite me and give me a fever of 105. The swamp will kill you if you let it. It would pull my house apart in a decade if I ever stopped mowing the lawn.
The worst thing the swamp produces is the horsefly. It's not actually only one kind of a beast; there's a handful of types. They appear after the midges and mosquitoes, but before the poison ivy, generally. They're the most vicious thing I can imagine. They attack like kamikazes, and get a blood meal from you with scissor mandibles. They make the end of my yard miserable for five weeks or so in the summer. Let's kill them.
Go down the basement and bring your heir and your spare.
You need a plan. It should contain all the information you need to build the thing, plus a list of all the items you need to purchase to make it. It should be a loopy looking long-haired- equation looking thing like that.
1/2" plumbing pipe, a clear plastic one-gallon jug with a screw lid, a funnel, a roll of 4 mil plastic, some punky wood strapping I dumped behind the shed 5 years ago.
The kids like the tinkertoy vibe of the plumbing pipe. I like the kids.
An 8" square of MDO left over from windowboxes.
If you can't use things for what they're not intended for, you have no business on the Internet.
You buy a 20" beachball at Wal-Mart, put a blessed halo around it with duct tape, leave a tab flap to pierce and hang the ball in the center with kite string. Spray paint the thing black while it's hanging. Horseflies are dumb. They see the ball swaying in the breeze and think it's a spherical cow or something. When disabused of this notion, they always fly straight up. They eventually make their way through the funnel and die in the heat of the clear jug. No bait or poison is necessary. The trap is a little more than a week old and the jug has thousands of the nasty bugs in there. For Amityville spectacle, some of the beasts lay their eggs in the corpses of their brethren before perishing, and the little sluglike larvae hatch and crawl around in there too. For a while. Hence the breeding cycle is interrupted, and next summer is made better now.
What do you know. It works. The kids can play in the yard again. If I'd have known it would work, I would have made a better looking one.
"If I'd have known it would work, I would have made a better looking one" would make an excellent epitaph for my grave, now that I think about it.
Here's a picture I took a day or two after I set it up. Not long after that, I had to empty it because the horseflies piled up to the top of the funnel]