Worm Food
Composting worms feed on kitchen wastes. Yard wastes, such as grass, cannot be composted in a worm bin because of two factors. The first is the easy formation and release of ammonia, ammonium and nitrate from these materials which, in the confined volume of a worm bin, are toxic to the worms. The second is the heat production associated with aerobic yard waste composting which, again, will kill off the worms.
Kitchen scraps acceptable in a worm composter include fruit and vegetable peelings, bread, tea leaves and coffee grounds and filters. Egg shells, which are slow to break down, should be crushed prior to placement in the worm bin. The calcium in the eggshells will help to offset the acidity in coffee grounds and tea leaves.
As with conventional home composting, the unacceptable vermicomposting materials include pet wastes, meat, bones, dairy products and oily and greasy foods. The ammonia in pet urine is toxic to the worms and pet wastes may also contain human pathogens. The unacceptable food wastes are slow to break down, putrify rapidly, are a source of odours and attract insects.