Daylily Pests

Daylilies are flowering perennials available in a wide range of colors. These low-maintenance plants do best in full-sun beds and borders and can handle hot, dry conditions, which many other plants often dislike. Daylilies are resilient, but there are a host of pests that can interfere with their lush foliage and bold flowers. Learn how to spot the signs of daylily infestation and prevent bugs from harming these dependable flowering plants.

Common Daylily Pests

Flower Thrips

Thrips are dark-colored, tiny winged insects that move fast. Flower thrips are so small they are hard to spot with the naked eye, but the damage they cause is visible. Adult and immature thrips pierce the surface of leaves and flower petals and suck sap from daylily plants. Flower thrip damage on daylilies appears as silver streaks or specks on leaves and flowers. A heavily infested plant will experience stunted growth, distorted leaves and flowers, and flower buds that fail to open.

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Photo by Raymond A. Cloyd

Treating Flower Thrips on Daylily Plants

Quickly remove thrips from daylily plants by spraying the plant with a hose to knock these pests from the leaves and flowers. Ladybugs and other beneficial insects eat flower thrips, so encourage these helpful insects and allow them to feed on the thrips. A severe infestation of thrips can be treated by spraying the entire plant with insecticidal soap. The goal is to cover the plant, so spray the underside of the leaves and the flowers to thoroughly cover the plant. 

Preventing Flower Thrips on Daylily Plants

Remove dead growth and debris from the ground surrounding the daylilies to reduce the risk of flower thrips. Insecticidal soap also works as a preventative measure for flower thrips. Spray the plants before the first sign of damage if you have previously had problems with these pests. Aromatic companion plantings, like chives, garlic, and catnip, are also effective at keeping flower thrips away from daylilies. 

Two-spotted Spider Mites

Mites are spider-like pests that bite foliage to suck sap from the plant. Two-spotted spider mites are more active during dry, hot periods. Signs of an infestation include yellow spots on the foliage. The initial damage may be hard to spot, but if the spider mites continue to feed on the plant, the sites will eventually connect, creating more extensive areas of damage. The damaged areas will ultimately bleach, and the entire leaf will die. Delicate webs strung between leaves are another sign of a two-spotted spider mite infestation on daylilies.

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Photo by Giles San Martin, unmodified, Flickr, Copyright CC By-SA 2.0

Treating Two-spotted Spider Mites on Daylily Plants

Spray an infected daylily plant with a garden hose to dislodge spider mites from the foliage and break up webs. Follow up by spraying the plant with an insecticidal soap. Apply the soap several times to eradicate all of the spider mites. Encourage beneficial insects like ladybugs and lacewings that feed on spider mites.

Preventing Two-spotted Spider Mites on Daylily Plants

Two-spotted spider mites often survive on dead growth and nearby plants during the winter. Remove dead growth after the first frost in the fall and remove nearby weeds so these pests have no place to hide out during the winter. Remove nearby plants early in the spring to reduce the risk of two-spotted spider mites infesting your daylilies.

Aphids

Aphids are sap-sucking pests that feed on plants like daylilies. Distorted or stunted growth are signs of an aphid infestation. These pests excrete a sticky waste known as honeydew, so the presence of honeydew indicates an aphid infestation. Further signs of aphids include ants that feed on the honeydew, and black sooty mold that grows on the honeydew. 

Treating Aphids on Daylily Plants

Predatory and beneficial insects like lacewings and ladybugs eat aphids, providing safe and natural protection. Multiple applications of insecticidal soap can also prove to be an effective treatment for aphids. Douse the entire plant in insecticidal soap and continue to re-treat every week to ensure good control.

Preventing Aphids on Daylily Plants

Prevent aphids on daylilies by routinely spraying the plant with water. A burst of water can knock the pests off the greenery. Spray the plant early in the morning to reduce the risk of mold or fungus developing on wet foliage. Aromatic herb companion plantings, like garlic, chives, and dill, are another method to keep aphids at bay.

Daylily Leafminer

Daylily leafminers are small black flies that lay their eggs on daylily plants. After the eggs hatch, the larvae feed on the inside of the leaves and create tunnels known as mines through the foliage. The mines appear as thin, white lines on the leaves. The tunnels mar the appearance of the foliage and ultimately kill the infested leaves.

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Steck, G. and Williams, G. Daylily Leafminer, Ophiomyia kwansonis Sasakawa (Diptera: Agromyzidae), new to North America, including Florida. 2012

Treating Daylily Leafminer on Daylily Plants

Leafminer damage rarely is harmful to daylilies. To treat a daylily with leafminers, you can remove severely damaged foliage. Prune leaves with tunnels created by feeding pests, which appear as white lines. Also, remove any dead growth. Leafminers will spend the winter in the foliage near the base of the plant, so remove damaged foliage as close to the ground as possible and clean up any debris around the plant. Destroy the clippings to prevent the spread of daylily leafminers. 

Preventing Daylily Leafminer on Daylily Plants

Daylily leafminers are almost impossible to detect until the damage appears, so prevention is practically impossible. Removing foliage at the first sign of damage is often the most effective way to prevent a leafminer infestation on daylilies.

Slugs

Slugs are a type of terrestrial mollusk that can do a lot of damage to plants. These vigorous feeders eat foliage, leaving rough, jagged notches or holes in leaves and a slimy trail in their wake. By damaging leaves, slugs render a plant unable to support itself and produce new growth. Plants damaged by slugs will not grow as big or may decline after severe damage. 

Treating Slugs on Daylily Plants

Slugs feed on daylilies at night, so go out in the evening when the slugs emerge to pick them from the foliage manually. You can set a slug trap by filling a saucer with beer. The slugs are drawn to the beer but will drown after they fall in.

Preventing Slugs on Daylily Plants

Slugs live in damp, moist areas, so eliminate any hospitable hideouts near your daylilies. Remove dead growth, plant debris, and mulch since this material retains moisture, creating a damp environment welcoming slugs. These pests are less likely to stick around if they do not have a safe hiding place.

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Author Alison Cotsonas - Published 08-04-2023