Adding fresh bedding to worm bins will reduce odors. In a worm bin, do not overload the bin with too much food waste until the worm population is established. Never add cheese or other animal products in any type of compost systems. Fruit flies are more of a nuisance than a serious problem. Minimize fruit flies in a worm bin by fully covering fresh food waste with several inches of bedding, and by covering the bedding with a sheet of newspaper, cardboard or plastic tucked in around the edges.
Rodents can be a problem.
The easiest way to keep animals from entering a worm bin is to keep the lid shut and meat wastes out. If there are signs of animals around the worm bin, place a sheet of wire mesh over the bottom of the bin or raise the bin off the ground 12 to 18 inches. Keep the worm bin lid latched or well secured if opposums or racoons are a problem.