Orchids: How to Identify and Control Common Pests

By Steven A. Frowine and National Gardening Association from Orchids For Dummies

11 of 11 in Series: The Essentials of Growing Orchids

When you first notice pests on your orchids, you need to promptly and properly identify them so you can be sure to apply the most effective control. In many cases, especially if there are many pests present, you'll have to apply control measures every seven to ten days, at least three times because eggs are resistant to the control and hatch later.

Aphids: These come in all colors — including green, red, pink, black, and yellow — and they're usually found on the new, succulent growth including the flower buds.

Look for clusters of aphids on flower buds and young shoots and leaves.

If you see clear sticky droplets anywhere on you plant, look out for aphids.
Mealybugs: The name of this creature pretty much describes what this insect looks like — mealy or cottony masses. It's found in similar areas as aphids — the growing tips, buds, and flower stems. One type is also found on the roots. Getting rid of this pest usually requires multiple insecticide treatments

Mealybugs look like white cottony masses.
Thrips: Thrips are miniscule buggers that look something like long gnats and are very difficult to see with the naked eye. Their damage is easier to detect — it shows up as light streaks on the flowers or stippling on the leaves. The flower buds are also usually deformed.
Scale: This is another creature that comes in various forms, but most have a shell that serves as a type of armor for the soft insect body that is protected by it. This shell must be penetrated by a chemical or by rubbing it off before you can kill the insect. They're frequently found on the undersides of the leaves near the middle vein of the leaf or on the edges of the leaf. They also commonly hang out on the flower stems.

Scale is a very common pest on orchids.
Spider mites: These tiny, fast-moving specks of red "dots" are often found when growing conditions are hot and dry. In extreme infestations, you'll see fine webbing on the leaves. Before the infestation gets this bad, the foliage will take on a stippling effect, which is a result of their feeding.

Spider mites are very small, hard-to-see pests that can be very destructive.
Slugs and snails: Snails and slugs usually come out at night, so look on the bottom of the flower pots. They love cool, damp spots.

Snails and slugs eat holes in flowers and leaves at night.
Roaches: Another very unpopular beast, cockroaches also feed at night and enjoy munching on flowers and flower buds.
Mice: Mice nibble at flower buds.
Bees and other pollinating insects: These don't cause any physical damage to orchids, but if they land on the flowers and pollinate them, the flowers will very soon collapse.

The pest-control methods in the following table are listed in their approximate order of safety and are readily available.

Common Orchid Pests and Their Controls
Pest	First line of defense	Second line of defense	Comments
Aphids	Wash off with warm water.	Insecticidal soap, Orange Guard (orange oil), horticultural oil, isopropyl alcohol	If aphids are on the flower buds of orchids, try repeatedly washing them off with warm water.
Mealybugs	Use a cotton swab drenched with isopropyl alcohol.	Insecticidal soap, horticultural oil, Neem	For orchids with mealybugs on their roots, remove the orchid from the pot, soak the roots in a solution of insecticidal soap for a few hours, then repot in a clean new pot with new potting material.
Thrips	Neem, horticultural oil, insecticidal soap	Malathion, Orthene	Malathion and Orthene are effective on a broad range of insect problems but they both reek; apply outside of living area.
Scale	Orange Guard; or dip a cotton swab into isopropyl alcohol and wipe across the armored shell of this insect. Make sure that you penetrate this shell.	Insecticidal soap, Neem, horticultural oils	Difficult to eradicate. Apply controls repeatedly to get rid of it.
Spider mites	Wash off with a strong stream of warm water.	Insecticidal soap, horticultural oils, Orthene	Prevent spider mites with proper watering; avoiding excessively hot growing temperatures.
Snails and slugs	Put out a shallow platter of old beer, and wait for these creatures to belly up to the bar at nightfall.
	Sluggo
Mice	Live traps	Old-fashioned snap traps. Peanut butter is an effective bait.
Roaches	Orange Guard	Roach aerosol sprays — use on the floor, not on plants.	Orange Guard both repels and kills roaches. And it smells good!