Mites are generally too small to be seen without a magnifying glass. They are brownish in colour and look like dust. Mites suck plant juices and leave foliage speckled and yellow. If not controlled the leaves will turn brown and fall off, and new growth will be stunted with deformed buds. Spider mites produce webs on the leaves to hide and feed under.
Plants growing in hot, dry locations are most susceptible to mite attack.
Take control measures as soon as you notice these pests because mites multiply very rapidly. Scale insects are oval bugs up to 4 mm in diameter that don't resemble any other pest. When I first encountered them I thought they were a fungus of some sort. Nope, they are bugs all right, with a brown shell-like covering. They can be found on stems and leaves and suck juices from the plant causing poor, stunted growth.