Pests on Lilies

Insects That Suck Out Fluids

• Aphids suck out vital fluids from plant leaves, stems and other tender parts of the lilies. They have tiny, soft bodies and narrow mouths that enable the insects to aspirate plant fluids. Aphids come in red, yellow, green, brown, black and red and are often wingless. Lacewings, lady bugs and syrphid flies are natural enemies of aphids. Prune evidence of aphids, such as stunted shoots, yellowed or curled leaves of the lily plant to get rid of small aphid infestations. Knock aphids off the lily plants with a strong spray from the garden hose. Use insecticidal soap for larger infestations, and make sure the spray douses the undersides of the leaves as well.

Insects that Suck Out Cell Content

• Thrips are narrow, tiny insects with the mature adult being 1/20 inch long or less. They have fringed wings and suck out the cell content of lilies and other plants. Thrips range in color from translucent to black, and many are brightly colored. Evidence of thrips is black feces on leaves and discolored or distorted plant sections. Spraying the thrips with a blast of water or pruning is an effective way to control small infestations of thrips. Neem oil and insecticide soaps are effective in controlling larger infestations, but often another treatment is necessary again 5 or 10 days later.

Chewing Pests

• Slugs and snails are mollusks that leave a silvery, dried trail of slime on the leaves or petals of lilies. Snails have an external shell but slugs do not. The mollusks chew on leaves and flowers, leaving them with irregular holes and susceptible to decay. They also clip off parts of the plant. Picking the mollusks off the lilies by hand and destroying them is effective in controlling small populations. Water the lilies in the late afternoon, and inspect the plants with a flashlight after dark in order to discard the most snails and slugs. Reducing hiding places is another way to prevent snails and slugs. Weedy areas, ground cover -- such as ivy -- boards, stones and other debris provide shelter for the pests. Metaldehyde baits are effective in reducing the population during warm weather and low humidity.

Flying Insects

• Bulb flies resemble miniature bumble bees. They are short, stocky and hairy. The bulb flies range in color from black to dark green. They have markings in yellow, gray or orange. Bulb flies feed on nectar and pollen in lilies. Prevention is key for these pests. Purchase disease-free bulbs and plants because bulb flies feed on diseased sections of plants. Discard or prune any diseased sections of the lily plant as soon as you spot them to prevent attack from these insects.