Orchids, like babies, can be easy or difficult. If you’ve decided to parent one, consider an easy phalaenopsis orchid (Phalaenopsis spp.). Commonly known as moth orchids, these affordable beauties bloom for months with minimal care that would drive their temperamental relatives to tantrums. Grow them outdoors in U.S. Department of Agriculture plant hardiness zones 10 through 12 or as houseplants elsewhere. Their few problems include occasional -- and readily treatable -- bug infestations.
Aphids, scales and mealybugs attack moth orchids, attaching to their leaves and stems and draining sap with needle-like mouthparts. Look for pear-shaped aphids on the buds, flowers and new shoots. Dome- to disc-shaped scales typically attack leaves, flowers or roots. A cottony, white wax covering distinguishes mealybugs from scales. They feed on blooms, on the axils where leaves and stems join and on the plants’ bases. All three produce honeydew, a transparent, sticky waste that attracts photosynthesis-blocking sooty mold. Don't confuse this goo with developing flowers' and leaves' natural, sugary sap secretions, also called honeydew.
On outdoor moth orchids, ants are like Mary’s little lamb. They follow honeydew wherever it goes, even stroking the abdomens of its producers to stimulate its release. They'll also transport the pests to other plants to build new colonies.
Moth orchids growing in excessively dry condition attract tiny winged thrips. Thrips scrape the plants' leaf and flower cells and consume their contents, leaving rough, silver-mottled foliage in their wake. They're so small that this damage is what alerts most people to their presence.
Nearly invisible, flat, red eight-legged phalaenopsis mites inflict severe damage by piercing moth orchids' leaves to access their chlorophyll. The affected leaves take on a silvery cast, then darken to rust-brown. As they molt, their discarded white skins litter the discolored foliage. Red, false and two-spotted mites also strike moth orchids. These spider-related pests pose the greatest threat to orchids stressed from dry, hot environments.
Treating Harmful Bugs
Remove small scale or mealy infestations by scraping them from the plants with a cotton swab dipped in 70-percent isopropyl alcohol. Spraying with insecticidal soap solutions suffocates all these pests. Prepare a batch of this kid-, pet- and surface-safe bug eliminator by mixing 5 tablespoons of liquid hand or dish soap in 1 gallon of soft water. Spray the plants until dripping, taking care to cover both sides of the leaves. Treating indoor orchids in the sink or shower eliminates mop-up. Rinsing outdoor ones with water a few hours after spraying them reduces their risk of sun damage.
Not all moth-orchid buds have mischief in mind. Outdoor moth orchids lure real moths to pollinate their fluttering, winged flowers. Harmful bugs invading outside plants attract their own following in a wide variety of predatory insects. Ladybugs, lacewings, parasitic wasps, syrphid flies and predatory mites are among the many insects to feed on moth orchids' pests.