How to Build a Gnat Trap. Do you spend your days swatting at flying creatures that seem to increase in number by the second? You probably have a gnat infestation. Gnats, also known as fruit flies, are pesky insects that love to take up residence in drains, on fruit and in the soil of indoor plants. Here's how to build a gnat trap using household items and reclaim your sanity.
Remove the lid from a glass jar and thoroughly rinse the jar with soap and water. Any jar will do, but the gnat trap will work best if the mouth of the jar is fairly wide.
Add 5 tbsp. apple cider vinegar to the jar. White vinegar will suffice if you don't have any cider vinegar on hand.
Cut a sheet of plastic wrap into two pieces of equal size. The plastic wrap should be large enough to cover the mouth of the jar, with about one inch to spare.
Place both sheets of plastic wrap over the lid of the jar and secure with a rubber band. It's essential to secure the plastic wrap, as the fruit flies are small insects that can escape easily.
Gently poke several holes in the saran wrap using a fork. It's important that the holes are not too close together and that there are not many holes close to the edge of the lid, as this would give gnats an escape route.
Place your homemade gnat trap next to the source of the infestation. If you have noticed the insects in more than one location, make several traps and place them around the house.
Enjoy watching your gnat trap become populated with the pesky fruit flies that had taken over your dwelling.