You do not need to add worms to your compost pile. Outside, composting happens with and without the help of earthworms. Worms will usually find their own way to a compost pile.
Coffee grounds, as an organic material, can be added to your compost pile. Worms like coffee grounds, so you may want to put a layer of coffee on the bottom of your pile to attract worms.
The more you turn the pile, the quicker you will produce compost. Many people would rather let their pile sit and let nature do her work over a several month period. If you turn your pile frequently, you may produce compost in one month. If you turn your pile once in a while, you may produce compost in 3-6 months.
Most commercially sold compost bioactivators contain microorganisms which will help your pile start composting. However, similar microorganisms are readily available in a handful of soil or finished compost.
With proper management, rats and other pests should not be a problem. Rats are attracted to food odors. By avoiding odiferous foods such as meats, dairy and oil, and mixing in or covering with a good layer of brown material (dry leaves, wood shavings, crumpled or shredded paper) odors will be filtered out.
When most people think of "earthworms", they usually mean "nightcrawlers," which can be 8-10" long and 1/2" in diameter. These nightcrawlers are different from red wigglers, although both may be called "earthworms" since they both are found in the earth.
Nightcrawlers are soil-dwellers, thus they like to burrow several feet below the surface. By burrowing, the nightcrawlers mix different layers of the soil, while creating tunnels which aerate the soil. On the other hand, red wigglers are surface-dwellers and prefer to live within the top 6" of the soil (which is why red wigglers prefer shallow boxes as homes). Red wigglers are often found among the fallen leaves of the forest floor, as well as in manure piles.
Worms do not have teeth, therefore they cannot bite you. Do not be afraid to hold a worm. Most people find that the worms are soft and ticklish.
The yellow liquid is not urine, which many people first guess. The yellow liquid, called coelomic fluid, is released when the worm is stressed, which often happens when students touch the worm. When a worm is placed on a student's dry hand, the worm's body will begin to dry out. The worm will start wiggling, trying to find its' way back to the soil or bin, then release a yellow liquid in order to make its' body moist again. Exposure to light also triggers the release of the coelomic fluid. This yellow liquid may smell like garlic, hence the scientific name Eisenia foetida. Foetida means smelly. When conducting experiments with worms, you may want to gently spray the worms with water every few minutes.
Almost everyone wants to know the answer to this question. Some species of worms can regenerate, or re-grow, a new tail, if their tail is cut off. However, a worm cut too closely to its' head will have difficulty growing a new tail. Most worms will not regenerate a head.
Generally, we tell students that if you cut a worm in half, you will most likely end up with two dead pieces of worms. However, if you are lucky, the piece with the head may grow a new tail, so you will have one alive worm and one piece of dead worm.
Some worms have a natural reflex, in which they will eject their tail when the tail is pulled. For example, when a bird catches the tail end of a worm, the worm would eject or sever its' tail from the rest of its' body. Thus, the worm remains alive and safe, while the bird gets only part of the worm.
Worm compost makes nutrients available to plants. When compost is mixed with water, it has the ability to hold many positively-charged mineral ions (cations), or nutrients, which can then be taken up by plants. Also, as worms process (digest) the food scraps, the nutrients in the food are changed into forms which can then be used by plants.
