Fruit Fly Trap (Customizable)

thingiverse

This is a compact and straightforward design for a fruit fly trap. The printed component merely screws onto an empty jar, which has a luring liquid at the bottom. Flies pass through the small slots into the jar and are unable to escape again. In addition, this makes a great package for gift cards or money. So don't buy unnecessary cards or envelopes and give a real useful present instead. It took about ten minutes to design and is a nice little example of how effective parametric CAD design with FreeCAD can be. Well, the ten minutes does not include getting the measurements and tolerances for the jar correct. :D By default this file fits onto LIDL discounter maribel jam jars. If you adapt this for other jars, send me the measurements and I will add them to this text. Please note that the design is intended to avoid over tightening of the lid. It simply pops back to its previous winding position. This is intentional. It won't fall off when grabbed by the lid either. Due to the open fly trap slots, it makes no sense to seal it with force like a jam jar. However, the FreeCAD file includes a spreadsheet with all required measurements, so you should be able to adapt the design to any jar in your household. There is no need to learn CAD to customize this thing. In addition, you can define the number of thread fingers the printed jar lid should have. You can also adapt the design to catch bigger flies by increasing the opening in the funnel as well as the number of openings. Once printed, simply screw the lid onto the empty jam jar and you are ready to go. There are numerous recipes available online. Essentially they all use vinegar, something sweet, and a drop of dish washing liquid to break the surface tension of the liquid at the bottom of the jar. The sweet component can be anything a fruit fly likes. Apple juice or some rotten fruit works well. Wine or special vinegar is also effective. It's just essential to give the trap some time. It may take up to 24 hours until the traps start doing their magic. Make sure not to place the jar next to a window or heat source. Depending on the amount of liquid used and the ambient temperature, a change is needed once a week or every few days. Placing it near locations where fruit flies congregate is key. So place the trap next to your kitchen sink or a fruit basket so the flies stay away from the good stuff. Update: I added a version with a more rounded lid. Update #2: Added an English LibreOffice file to print as how-to use instructions.