You should ultimately be feeding over three times the weight of your worms per week, but when first feeding, bury food scraps in a section of your bin where you'll remember. Put in about 1/2 the weight of the worms you start with. Bury the scraps in an area where the worms can get away from it if the food heats up any; as it starts to break down, it'll draw the worms and they'll feed. Start this on a once per week schedule and add feed only when the worms are congregated in the food area. Next time bury the food away from the first location so they can avoid any heat...and on and on. Gradually increase the amount of the food as the worms get used to the routine, and you may have to feed a little more often as this happens. Monitor your worms, and add or decrease feed as needed. Common sense goes a long ways here. They'll gradually consume up to 1/2 their body weight per day, and in some cases even more, and you have to remember that as they reproduce, the amount of food required goes up. An over abundance of food can cause the worms to produce more, as worms will breed up, or down, to handle the abundance of food, as long as they still have adequate space requirements.
Do Feed
Feed egg shells,vegetables and fruits, coffee grounds or tea bags including the bag or filter, any composted plant residue (includes grass clippings, but let them compost past the heat stage), livestock manures past the heat stage, grains, chicken layer mash, etc. When feeding any commercial livestock feed you should check the label for antibiotics, etc., as they are counter productive. NEVER mix grains in your bedding unless your beds are deep enough for the worms to escape the heat. I always top feed my grain. Newspaper and corrugated cardboard are good. Powdered milk and non dairy creamers work just fine.
Do Not Feed!
Meat and dairy products, as they draw pests to your bin, uncomposted grass and plant clippings, as they will heat up your bin until they've passed the heat stage (they may also have been sprayed with pesticide). A few citrus rinds are ok, but too much at one time is not good...the fruit and pulp are ok, and composted rinds. Pineapple is very highly acidic. Be sure it's well composted, if you're going to feed it at all, especially in a home composting bin. Uncomposted manure is too hot, and may contain wormers if it's fresh. I will not feed dog and cat manure at all. Poultry manure is great if composted, but can be deadly if fed too fresh, as it's high in nitrates, salts and ammonia. Worms hate oils and fats. Bob Ingram
Fatal Foods
There are no foods that are considered toxic to worms, not even very acidic foods like tomatoes or pineapple, or those which contain protein degraders, like mango. All of these foods are routinely fed to worm beds very effectively. The issue becomes murky when the ONLY food source going into the worm bed is one that is highly acidic, salty, or irritating, but when used in combination with other organic materials there is nothing that mammals can eat that worms cannot effectively process. There is one worm system in Australia, for instance, that processes vineyard waste, which has a pH of 2. This is some seriously acidic stuff, yet the worms are working happily and efficiently through it. There is a fruit stand on the island of Kauai that is processing all of their spoilage in an onsite worm bin, spoilage comprised of mangos, bananas, pineapple, coconut, mountain apples and other indigenous fruits. Again, this system is working beautifully. There are numerous worm systems in the pacific northwest, land of the coffee addicts, processing nothing more than coffee grounds (with some filters mixed in). In Florida there are worm systems processing culls from citrus orchards, rind and all, very effectively. There are worm systems throughout the world processing post-consumer food waste, which is seriously salty stuff, with no problem at all (though the resulting castings tend to be high in salts).
In areas of India, where vermicomposting is far ahead of us here in the US, they had to learn how to manage their foods so that they could be effectively used in worm beds because of the heavy use of pungent spices that would drive worms from the bed or kill them. Many Mexican worm composters had the same challenges, yet they discovered that by mixing with good bulking agents and allowing the material to do a bit of precomposting first the pungent, irritating constituents were remediated.
Want a really weird one? If you have a neighbor who keeps a piece of cardboard beneath their car to catch oil leaks, lift up that piece of oily cardobard once. You will almost always find earthworms coiled beneath the oil spot. Even motor oil, which is after all derived from living plant and animal matter, supports microbes which support earthworms.
The bottom line is that worms can eat ANYTHING that was once living or part of a living thing. There is no list of toxic foods because, well, there really aren't any.
