Both usually hide in loose soil or under vegetable debris, boards, sacks, or pots on damp ground during the day, and are active at night. Although they normally feed on decaying vegetable matter, they sometimes eat roots and tender plant parts, especially those of bedding plants and seedlings. Their hiding places should be eliminated as far as possible. A number of common pesticides can then be sprayed under boardwalks and benches, along foundations, and in other infested areas. The adults have 4 pair of legs instead of the 3 pairs possessed by insects.
Some species are ectoparasites of man.
Others are among the most important of the plant pests, and commonly infest house plants. All spider mites are pests of cultivated plants, particularly under dry and warm conditions. They are oval in shape, greenish, yellowish, or reddish, and are so small that they are barely visible without the aid of a magnifying glass. Spider mites are found mainly on the undersurfaces of leaves, but in heavy infestations a small percentage may be seen on other parts of the plant. When the mites are very numerous, a silky webbing may be found covering infested areas and extending from leaf to leaf to cover the entire plant.