Soil mites are arthropods that are attracted to moist soil and feed on decaying organic matter. They are usually found in flower beds, piles of leaves, wooded areas, compost heaps, etc. Soil mites are tiny, less than a millimeter, have six legs, and may look like little brown or white spots that move around in the soil. Soil mites do not harm plants, they help breakdown organic matter to help the plants get needed nutrients from soil and actively aerate the soil; however, they also carry parasite eggs, like tapeworms, and disease-causing bacteria.
Spider mites are arachnids. While there are many different types of spider mites that survive in different climates, the majority like warm, dry conditions. They are no more than a millimeter long, have eight legs, and can be reddish orange, green, yellow, black, white, brown, and translucent; some have two spots. Spider mites feed on plant materials which can cause plant weakness, stunted growth, and death of the plant.