How to Identify and Control 13 Common Orchid Pests

Most orchids are epiphytes, non-parasitic plants that use trees for support but take nothing in return.

Other orchids are rock-dwelling lithophytes, semi-terrestrials living in leaf litter, and soil-dwelling terrestrials.

Orchids typically favor bright, indirect light, moderate moisture, and loose, well-draining soil or potting medium.

Gardeners can enjoy these diverse plants outdoors in Zones ranging from 2 to 9, depending on the species, and indoors as houseplants.

Our guide to growing orchids has all you need to enjoy these unique plants at home.

This article zeroes in on 13 common pests you may encounter during cultivation.

Here’s what we’ll cover:

Whether you grow your orchids indoors or out, pests may infest your plants at some point, especially if they are under stress as a result of overwatering, lack of nutrients, and/or overcrowding.

Here are 13 common pests and appropriate measures to take to address them.

1. Ants

Ants are members of the Formicidae family. Except for a few species, like the long-bracted frog orchid, Coeloglossum viride, they are typically not attracted to orchids.

What attracts them is the sticky “honeydew” excreted by sapsucking pests like aphids, mealybugs, and whiteflies. Once they find a sweet supply, they move in and colonize garden and potted orchids alike.

If you see ants on flowers, foliage, or potting medium, examine the upper and undersides of the leaves.

If you notice additional crawling or flying pests, eggs, honeydew trails, leaf anomalies, and/or webbing, your orchid may be infested with sapsucking pests, which we’ll talk about later in this article.

To rid your orchids of ants, you’ll need to address the pests that left behind the honeydew they are attracted to.

The following control measures will help you eliminate both the ants and the sapsuckers:

Repot your orchid for a fresh start. Unpot the orchid, rinse the foliage to dislodge the ants, then repot in fresh medium after sanitizing the existing container with a 10 percent bleach solution and allowing it to dry.

In the garden, spray the pests away with the garden hose set to a gentle setting.

After washing away as many pests as possible, treat indoor and outdoor orchids with a horticultural oil, like neem.

2. Aphids

Aphids are soft-bodied sapsucking insects in the Aphididae family that use chewing mouthparts to feed on plant juices.

There are many different types that can attack orchids. Telltale signs include foliar deformity, honeydew trails, and visible pests on buds, leaf tops, undersides, and stems.

Honeydew may appear as a grayish and fuzzy coating on the orchid foliage because it has become a breeding ground for powdery mildew, a fungal condition.

Avoid overwatering and overcrowding – aphids like humid, wet conditions.

Dislodge and wash away the pests with a watering can or garden hose. Follow the water rinse with an application of organic neem oil to address both the pests and the fungal infection.

Severe infestation may warrant repotting indoor orchids in sanitized pots with fresh growing medium.

3. Caterpillars

Caterpillars are the immature larvae of butterflies and moths in the Lepidoptera order.

These worm-like pests are voracious feeders and a large infestation can kill your orchid.

Many are “host specific,” like the monarch that feeds on milkweeds, but others are not as particular.

Because they feed in the daytime, it’s usually easy to spot caterpillars chewing holes in the flower petals and foliage of your orchids.

You are unlikely to find them on indoor orchids, they are much more of a problem outdoors. There are several approaches to managing them in the garden:

Hand pick and squash the pests or drop them into a bucket of soap sudsy water.

They are active at night and leave specks of black frass and molted exoskeletons in their wake.

If you’ve had trouble with cockroaches in the past, you can place screening over the drainage holes of pots before adding potting medium to make entry more difficult.

Store food securely to avoid attracting the pests and seal up potential entry points into your home.

You can treat the orchids and the potting medium with neem oil, which is effective at killing these pests.

For potted orchids outdoors, apply food-grade diatomaceous earth over the foliage and potting medium to disrupt their ability to feed.

Chemical measures are generally ineffective because cockroaches rapidly develop pesticide resistance.

5. Fungus Gnats

Fungus gnats in the Orfelia and Bradysia genera are tiny flies that often live in potting media.

They are similar to ants in that they do not cause damage, but are an indicator of a problem in the growing environment.

Where conditions are wet, and plant material is decaying, fungus gnats proliferate, so avoid overwatering and ensure you use pots with ample drainage holes and appropriate, well-draining potting medium.

Always purchase good-quality potting medium to avoid products that harbor fungus gnat larvae.

You can place yellow sticky traps near the orchids to catch the pests, but if the infestation continues unabated, it’s a good idea to repot your orchid in fresh potting medium.

Neem oil or organic pyrethrins can be used to treat an extensive infestation, especially if multiple houseplant specimens are affected.

Extensive infestation may warrant the use of an organic pyrethrin product.

Our guide to controlling fungus gnats on houseplants has more information.

6. Grasshoppers

Grasshoppers in the Romalea family, sometimes called “lubbers,” are most likely to pose a challenge in outdoor settings.

These hopping arthropods are easily seen feeding on foliage during the day. Unchecked, they can strip an orchid of its leaves and destroy the roots, too.

Keep the garden free of tall weeds that may harbor grasshoppers. Since they don’t move very fast you can knock them off the orchid into a bucket of soapy water or hand pick the pests.

Neem oil and pyrethrins are effective in the case of damaging infestations or a synthetic pyrethroid can be used to combat large grasshopper populations.

Invite birds to the yard with houses and birdbaths so they can feast on the pests.

7. Mealybugs

Mealybugs are members of the Pseudococcidae family of “unarmored” or soft-bodied scale insects.

They are white with waxy bodies that feed by piercing plant tissue and sucking out the juices.

When you see them, you can handpick the pests or use a cotton swab dipped in 70-percent isopropyl alcohol to remove them. Rinse the foliage afterwards.

Neem oil, insecticides containing pyrethrins, or synthetic permethrin are effective in the case of a large infestation.

After treating, unpot, sanitize and rinse containers, rinse the orchid and its roots, and repot in fresh potting medium.

Avoid overwatering and overcrowding. As with aphids, mealybugs like conditions that are wet and humid.

Learn more about identifying and managing mealybugs in our guide.

8. Orchid Blossom Midges

The orchid blossom midge, Contarinia maculipennis, are winged insects that resemble tiny gnats or mosquitoes.

Orchid blossom midges lay eggs in openings at the tips of the flower buds. When the eggs hatch, the larvae feed inside the buds causing “bud blast,” the discoloration and disfigurement of buds and blossoms.

In advanced cases, blooming is reduced as buds and flowers wither and drop.

Remove and destroy damaged buds and blooms and discard them in the trash.

Treatment is challenging because midge larvae are cocooned inside the buds, and neither organic nor chemical treatments effectively reach them.

Other susceptible flora includes bitter melon, eggplant, hibiscus, jasmine, pepper, plumeria, tomato, and white mustard cabbage.

As more research into this pest is conducted, more plants may be deemed vulnerable.

9. Scale

Scale is a sapsucking “armored” insect with a waxy protective shell. It’s a member of the Coccoidea family of the order Hemiptera.

The adults are wingless pests that attach themselves permanently to plant tissue and remain there like barnacles on the bottom of a boat.

Damage includes yellowing leaves, growth anomalies, and leaf drop.

Excreted honeydew attracts ants and is also a breeding ground for sooty mold. This fungal disease covers foliage with a black ashy coating that can impair chlorophyll production and photosynthesis.

The best defenses against scale are meeting all cultural requirements for sunlight and water and avoiding overcrowding.

If you notice these pests on your orchids, you can swab with 70-percent isopropyl alcohol and rinse.

Once moistened, you may be able to use your fingernail to gently lift the scale insects off and dispose of them.

Sprays of neem oil or products containing imidacloprid, a synthetic nicotine, treat sapsucking scale effectively

Learn more about how to deal with scale insects in our guide.

10. Slugs and Snails

Slugs and snails are night-feeding gastropods that move by a muscular foot and thrive in damp conditions.

These are generally going to be problematic outdoors or in the greenhouse, rather than in your living room.

Their feeding causes irregular holes in the foliage with smooth edges, often right in the center of the leaves rather than along the edges.

They leave a tell-tale trail of silvery slime in their wake. By morning, the pests themselves have unusually vanished.

Avoid overwatering and keep the growing area free of debris and empty flower pots that make comfortable hiding places for snails and slugs during the day.

Go into the garden at night to remove them by hand and drop them into a sudsy bucket.

11. Spider Mites

Spider mites are tiny arachnids in the Tetranychidae family and are common houseplant pests.

They pierce plant cells one at a time to feed on juices, causing speckling on the foliage and stems that merges, making leaves look bronzed.

With large populations, webbing may be visible, and foliar deformity and plant death may occur.

Rinse houseplants with water to dislodge pests and webs from foliage.

Use a soft-spray setting of the garden house for outdoor specimens.

Apply organic neem oil or other horticultural oil to suffocate the spider mites on contact.

Chemical miticides containing bifenazate are formulated especially for mite control and are effective against numerous mite species.

Learn more about spider mites and how to control them in our guide.

12. Thrips

Thrips are flying sapsuckers with uniquely fringed wings and asymmetrical mouths in the Thysanoptera order. These pests may proliferate under hot and dry conditions.

Their feeding causes foliar anomalies, like stippling, a silver sheen, and a papery texture.

The buds and flowers may also be affected by deformity and a discoloration called “color break.” Black frass excrement may be visible on the foliage and stems.

Keep orchids moist to create conditions unfavorable for thrips.

Place yellow sticky traps around your orchids to catch as many as possible.

Spray with neem oil if the infestation is severe.

Imidacloprid, a synthetic nicotine product is also effective if you prefer a chemical option.

See our guide to thrips for more information.

13. Whiteflies

Whiteflies are sapsuckers in the Aleyrodidae family. These white-winged pests are often found clustered on the undersides of leaves.

Brushing past them causes them to lift briefly into the air en masse, like a puff of powder.

Whiteflies prefer warm, humid conditions. Damage includes leaf yellowing, desiccation, and eventually leaf drop.

In addition, adults excrete honeydew that attracts ants and creates a breeding ground for sooty mold.

Avoid overcrowding your plants as it might raise the ambient humidity.

Install yellow sticky traps near your orchid to capture as many whiteflies as possible.

In the garden, you can set silver reflective mulch around plants as a deterrent.

Silver mulch is reflective and bright. Place it around garden specimens as a protective barrier to deter whiteflies.

Treat with organic horticultural neem oil to reduce populations and if the problem gets out of hand and you need to resort to chemical intervention, imidacloprid is effective.

Learn more about whiteflies and how to control them in our guide.

A Note on Greenhouse Growing

If you are growing multiple orchids in a greenhouse setting, here’s a biological approach you can try: introduce natural predators to feed on orchid pests.

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