Two-spotted spider mites are very small and damage is often noticed before actual mites are seen. Damage begins as dull stippled foliage as seen here on Moonflower (Ipomoea). Closely inspect plants in warm, dry locations in the greenhouse. Use a 10x handlens and look on the underside of leaves for eggs, nymphs and adults. For more information see the fact sheet, "Managing Two-Spotted Mites in the Greenhouse " on the UConn IPM website.