Fruitfly trap lid

Note August 2020: Turns out my mason jars were 'wide mouth'. So I've finally designed some for what I take to be 'standard' sized. Pictures coming.

Designed to screw on the top of a mason jar with a ring/collar screw top thing. I happened to have these 1-cup (250ml) jars hanging around.

Fill the jar about half way with just a drop of dish soap, and a mixture of about half vinegar and half water. (Apple cider vinegar is recommended, but I've tried others and they work fine. Actually, you can use it full strength; I just was running low and got cheap.) Put the lid (cones pointing in/down) over the mouth of the jar and secure with the ring. Leave wherever your fruitflies seem to be. You will be amazed.

The theory: Vinegar attracts the fruitflies, the conical shape of the lid-holes make it easier for them to get in than to get out. The dish soap reduces the surface tension of the vinegar/water so when they touch down the fruitflies drown.

I've added a chunk of dying watermelon I dropped on the floor to one. They really seem to like it. In the past I've used a slurry of flour and yeast, worked but not as effective. Vinegar all the way.