A hand lens is helpful in
identifying these pests on plants.
Aphids, mealybugs, and soft scales use their mouthparts to suck
the sap from plants. They can curl, yellow, or stunt leaves and can
reduce flower production and stem growth. All three pests also
excrete a clear, sticky liquid called honeydew. Black sooty mold
fungus can grow on honeydew, covering leaves and making them
Aphids, such as the melon aphid, Aphis gossypii,
are small (1 to 2 mm long), pear-shaped, soft-bodied insects with
two tubelike projections called tail pipes sticking out from their
abdomens. Aphids tend to cluster in groups. They feed on young
growth, flower spikes, and developing flower buds. Aphids can cause
flowers to become mottled and distorted. They are attracted to the
fluid excreted by some orchids when they flower, and they are highly
attracted to Cymbidiums.
To minimize orchid pest problems, implement such cultural
management strategies as prevention, sanitation, and plant
inspection. Prevention is the best strategy for managing orchid
pests. Proper cultural conditions, such as the correct amount of
water, temperature, light, fertility, and humidity, minimize
potential pest problems. Many reference books and manuals on orchid
culture are available. Be sure to know the cultural practices of
specific orchids being grown.
Sanitation is another strategy to prevent orchid pest problems.
Remove all plant debris and old orchid medium. Also, remove old leaf
sheaths to eliminate hiding places for mealybugs and scales. Inspect
plants on a regular basis by looking underneath leaves to detect the
presence of aphids and spider mites. If pests are present, use a
hard stream of water to dislodge insects and mites.
Insecticides and miticides are another option when dealing with
orchid pests, especially when populations are high. Insecticides
such as insecticidal soap, malathion, acephate (Orthene), diazinon
(Knox Out), chlorpyrifos (Dursban), and bendiocarb (Turcam/Dycarb)
control aphids, mealybugs, scales, and thrips.
You can also use biological control to deal with insect and mite
pests. Biological control involves the use of a pestís natural
enemies, such as parasitoids, predators, and entomopathogenic fungi.
Be sure to control ants, which are attracted to the fluid extracted
by orchids, because ants protect aphids, soft scales, and mealybugs
from attack by natural enemies. Consult biological control supplier
catalogs for natural enemies available for each insect and mite