Pests That Feed on Juices

• Aphids and thrips can cause extensive damage to orchids by feeding on the plant's juices, according the American Orchid Society. Both aphids and thrips' feeding result in distorted leaves, poor growth or stunted plants. Despite their small size, but much like aphids, mites can do considerable damage to orchid plants. They, too, feed on the plant, sucking out chlorophyll and sap resulting in silvery leaves, or in more extreme cases a diseased plant. Like aphids, whiteflies suck the plant's sap, weakening it, sometimes causing it to die. Gardeners may see the handiwork of aphids and thrips before actually seeing the pests themselves. Aphids are small, 1/8-inch long insects with a pear-shaped body. Thrips measure about 1/16 of an inch. Aphids have long legs, antennae and may be black, white or greenish in color.
  
  

Pests That Destroy Foliage

• Caterpillars like orchids' foliage and will quickly feed on a plant. Their damage aside, given their cylindrical shape and numerous legs, caterpillars are generally easy to spot on an orchid plant.
  
  

Pests That Destroy Flowers

• While they are more common to orchids grown in a greenhouse, roaches tend to eat the flowering portion of orchids. In addition to foliage, the American Orchid Society states that caterpillars also feed on the flowers of orchid plants.
  
  

Pests That Eat Multiple Parts of an Orchid

• Scale, the most common pest of orchid plants, according to the American Orchid Society, multiply quickly and feed on several parts of an orchid plant. Like scale, snails and slugs feed on just about every part of an orchid. Both pill and sow bugs feed on decayed plant material.
  
  

Control

• The American Orchid Society recommends practicing caution in buying orchids from a reputable source because anything less may result in the purchase of an infested plant. Sanitation and good cultural control are the first best defenses against serious pest problems. For example, diligently discard old potting materials and plant debris that may harbor pests and spread to other plants. Provide orchids with the proper amount of water, light and other environmental needs to further reduce the likelihood of pests. In some cases, gardeners may opt, or need, to take additional measures of control such as using insecticides, baits, repellants or simply allowing predatory insects to follow their natural course.