This recipe comes to us via Thomas Werner, a biological sciences professor at Michigan Technological University. Use it to attract moths for fun and enlightenment.
The bait has two basic components: overripe, fermented bananas and a solution of beer, brown sugar, apple juice, grape juice, and molasses. For the banana “base” take 10 or more pounds of peeled, overripe bananas and mash them in a large Tupperware container, and then let the mush ferment for two or three days in the closed container at warm temperatures. Occasionally stir the mixture during the first two days. Decant and discard any liquid that accumulates. Prepare the solution that will be added to the fermented banana base as follows. In a 5-gallon pail, mix 48 oz. of red grape juice, 32 oz. of apple juice, 10 Ibs. of dark brown sugar, 5 bottles of beer, and 16 oz. of “robust” molasses. (Avoid ingredients with preservatives.) Keep the pail loosely covered and at warm temperatures for three weeks or more prior to use, stirring every few days to be sure all of the sugar is dissolved.
Prior to use, stir in a few cups of the above liquid mixture to the banana base, and then spoon the resulting banana/liquid mixture into a round, flat plastic bait pan, and place in the trap. The bait will improve after a few days in the field. When humidity is low, add some of the liquid mixture to the bait every other day or so to keep the bait adequately moist. Also, check to be sure visiting moths haven’t imbibed all the free liquids; this sometimes happen on nights with elevated activity.
It is best if the bait is a little “tacky” so that there is a substrate on which the moths can rest while feeding. You may use the same starting bait over a three-to five-week period, adding a spoonful or so of the fermented bananas and a little of the liquid mixture from time to time. After using the bait repeatedly, it may appear “caramelized,” but will still be effective.