Invariably, no matter how faithful you are at guarding your worm bin, critters will get into your worm composting bin. Those critters run from harmless and benign to downright repulsive and harmful.
There are many critters that actually help your worm bin thrive.
Isopods and springtails are a couple of compost bin invaders that actually help break down food waste into nutrient rich worm and critter castings. They are good inhabitants and should be kept, if possible.
There there are the not so great worm composting bin critters. Those are bugs and mammals that attack worms, eat their cocoons or compete with them for food.
Some of those harmful pests of your compost bin are mice, rats, roaches moles, earwigs, mites, flies, centipedes roaches and ants and millipedes.
Kill roaches where you find them and remove the bin to an outdoor area immediately if they are found in your worm bin. Call a pest control specialist if you believe that you have roaches in your house. The worm bin most likely did not bring the roaches in. They were probably attracted to your worm bin because it was moist, warm and filled with things that they like to eat.
Mice and rats will feed on food in your composting bin and not usually the Redworms themselves. They will eat the food meant for the worms, they will tunnel through the worm bedding and they will use your composting bin covers as nesting material. There are humane traps on the market that can help you get rid of mice and rats.
Moles are also a major pain and they will invade your worm beds from the bottom, tunnel through the bed and feast on the worms. You will have to poison, trap or kill moles or you will lose your worms.
Millipedes and centipedes will eat small worms and cocoons. Smush them when you see them. The same goes for nasty earwigs. Have gloves on hand and smash them between your thumb and forefinger when you come across them in your worm composter.
Ants will also compete for food and they will carry the food away to their ant world.
Flies will not carry your worm bedding contents away but they will lay eggs in the worm compost bedding and the larvae will hatch and eat the food and make a stinking mess of your worm bin.
Pests are drawn to food. The only way to stop them is to keep your area clean, keep the worms indoors, or have a tight fitting lid on your worm beds/bins so that nothing can get into your worm bedding.
Practice common sense composting and keep your area open and clean. Debris provides hiding places for vermin and the vermin will then be attracted to your worm bin.