For next to nothing you could enjoy your garden without pesky flies landing on your food, landing on your sun drenched body and buzzing about whilst contributing very little to your garden! (if you want to be pedantic they are waste management in the ecosystem - I just don't like their methods!).
Blue bottles in my garden can be quite a problem. They enjoy chowing down on animal poo, anything dead, random food left out and I've even seen them swarming around dead snails! ...and they aren't shy about traveling! or reproducing!
Luckily, if you can break their cycle of reproduction early on in the season you can enjoy your outdoors without the sticky poo feet mob acting like they own the place. Simply deploy this trap when you first get a whiff of fly buzzing and the females will all come and lay their eggs in your trap... thus breaking the cycle!
So, Basically with a bottle, some tape, scissors and string.... you can make the perfect fly trap! The bait of choice is raw chicken lightly splashed with water!
Rest assured - no pollinators will be attracted to this trap (unless they're extra freaky and want to eat rotting meat). I've only ever caught flies.
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Step 1: You Will Need...
A 1.5/2L bottle. The bottle should be large enough to allow the trap to work properly, we don't want flies standing on top of bait and hovering out of our trap.
Tape should be sufficient to construct this trap. I choose to use duct tape because it seems to work well and is quite hardy when it's outdoors.
Hook to hang up our trap (optional). I have had problems with foxes trying to eat the bait so I decided this was a simple solution. You may well find a spot off the ground to perch it if hanging it up is too complicated.
String due to the disposable nature of this trap and the fact that it can be disposed off within a couple of weeks (or sooner) means that any string will likely suffice. If I had a nylon sting or wire I could have used that but it's by no means essential.
Scissors, hammer and a screw. The scissors are the safest way to cut the bottle. Please do not use a knife! You are likely to cut yourself as this is a surprisingly tricky materiel to cut safely and you won't get a neat cut anyway!. The hammer and screw is simply to make holes for the string. You can perhaps improvise. Again, Please do not use a knife!
Step 2: Carefull Does It!
We want to cut high up the bottle. The higher up we cut, the "deeper" the trap will be.
Squeeze the bottle together as shown. Cut as straight a line as you can keeping your other hand out of the way of the blades! We don't want to give the flies a taste of human blood which will no doubt spray all over the half made trap!
If you are adamant about using a knife, please cut away from yourself and onto a chopping board ensuring hand/fingers are well clear!. Then find another bottle because you probably messed it up!
Step 3: It's Coming Together!
We flip over the top of the bottle, the one we've just cut off. Push it down firmly so that the edges align. I'd be surprised if there is a risk of cutting yourself here.... but stranger things have happened, so do take care.
Step 4: Feather and Stick
Take a length of duct tape and feather it as show. You don't have to be too neat and you can do this is sections if you like. Push the centre of the tape along the rim of the trap and then fold down all the little flaps. This should keep the flies in, keep the smell from the bait coming out the entrance... and give the trap 50% of its final "stuck togetherness".
Step 5: Hang This Life Changing Device Withing 15M of the Problem Area.
I say 15M because under certain circumstances this can pong! Generally it will attract flies from quite a distance due to their subtle attraction to dead and rotting things. It's not always smelly by-the-way, I think it depends on a lot of factors like humidity, temperature, age...
Make holes for the string. The safest way I could think to do this was a hammer and a screw. You want to aim so that both layers of the plastic (i.e the base and the spout bit) are punctured with the same hole - This will ensure the string supports the upper and lower part simultaneously adding 50% more strength (tape + string = 100%!) . Once you're through you can manually thread the screw further to widen the hole.
Thread the hole. You can add a bit of tape to the end of the string and tidy it up with scissors to make it easier to thread. Loop it around as show, or if you like, use a different configuration. I would advise you tie each end of the string together.
Step 6: What a Delicate Beauty.
OK, we're done!
The last thing to do is to bait your trap. I've tried a number of left over raw scraps of meat and I pretty much just use chicken now. Processed/ red meat/cooked meat doesn't seem to do it for them. Fish smells too strong in my opinion. Raw chicken works every time. I add a tiny amount of water just to keep it in a state of decay and to stop it drying out... but not to cover the bait! Having some water around gives the flies an out (morbid joke, I value all life forms). Just a little splash around the bottom. You do not need much meat. A couple of 1 inch cubes is a good estimate - proper meat though, stuck through the mouth of the trap.
It's not the prettiest of items but then, it is a fly trap. There are a few options available to you. Firstly, find a tinted/darker bottle - the smell is what attracts the flies. Secondly, decorate it with some paint or glue some random stuff to it? Thirdly, you could hang it in a shrub or from a tree.
Usually the majority of flies will have been trapped in a couple of days - weeks. If you feel the trap is full, has gone too gross or it's been more than 2-3 weeks CAREFULLY, AND I MEAN CAREFULLY take the trap down and immediately bag it with a trash bag and tie it off (not the backwards flip method!). I recon this is a bio hazard by this point. Chuck it in another bag! You want to be sure the bag is not going to leak because, spoiler alert, the trap is full of fly eggs, maggots, dead flies. You throw out the entire trap in one fluid motion so you are not actually exposed to this horrific image I've just painted!
Now, enjoy your food, the sun, the outdoors free of that annoying buzzing noise and fly licks!
Rinse and repeat - Only joking! do not rinse and repeat!
Step 7: And Lastly...
To convert it to a trap for fruit flies simply swap the raw chicken out for some sugar + water + small amount of dish soap to (break water tension) + little bits of apple (last meal).
Top the trap with cling-film/saran wrap with a few small holes poked in it and secure with an elastic band.
Most will fail to escape the bottom chamber. Some will ultimately escape... they are essentially "gladiator" level so I would personally treat them well and allow them to come and go as they please. But that's just me.