Spider mites are very small, so they can’t be seen with the naked eye, but they can cause a lot of damage. The first sign of their presence is pale, dirty-looking patches of foliage. The simplest way to confirm their presence is to hold a piece of paper under the foliage that looks suspicious. Next, shake the foliage vigorously and watch for what looks like specks of dust to fall on the paper. Watch these specks closely. If they start to move, they are most likely spider mites.

To control spider mites, spray the plant with Bonide All Season Horticultural Oil, Bonide Super Soap, or Fertilome Spinosad Soap. Products containing bifenthrin also give good control. Thorough coverage is essential. Make sure to spray under the leaves. Also, avoid spraying during the heat of the day. Do not spray horticultural oils when the temperature exceeds 90 degrees, or it may burn the foliage. Do not spray blue spruce with horticultural oils.