Spider mites are tiny insects invisible to the naked eye. Adults feed by inserting their mouthparts into the foliage and withdrawing plant fluids, which results in a speckled appearance to the foliage. This ‘stippling’ increases in intensity until the foliage can appear bronze or bleached depending upon the host plant. Severe infestations result in needle drop. Webbing of fine silk surrounding the needles and twigs often accompanies high populations, protecting the mites from natural enemies. A well timed spray using horticultural oil is the preferred treatment to control spruce spider mite.