WSU Extension


Daylily gall midge 

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Caption: thrips damage on gladiolus
Photo by: R.S. Byther
Daylily : Thrips
(revision date: 3/10/2017)

Several species of thrips may be found on daylilies. Thrips are tiny (usually less than 1/8 inch long), fast-moving insects often found on leaves and between flower petals. Adults are typically yellow to brown; nymphs are usually yellow to whitish. Both immature nymphs and adults may feed on leaves and flower buds. A common symptom of thrips feeding damage is the presence of silvery streaks or speckles on leaf and flower tissues. Typical thrips damage is primarily cosmetic, but stressed plants or hot, dry weather conditions can result in more serious damage. Heavy infestations may cause leaf and flower stunting and distortion, and buds may die and drop from the plant without opening. Because of this, damage caused by thrips may be confused with that caused by daylily gall midge larvae. However, gall midge larvae are both legless and wingless and feed exclusively inside flower buds.
Management Options

Non-Chemical Management
  • Provide proper nutrition and soil moisture. Excess nitrogen and dry conditions make daylilies more susceptible to thrips damage.
  • Natural enemies including predaceous thrips help control populations of plant-feeding thrips. Avoid use of broad-spectrum insecticides to conserve these beneficial insects.
  • Sprinkler irrigation or heavy rain may help control thrips populations.
  • Control weeds in and around the garden.
Select non-chemical management options as your first choice!

Chemical Management

Apply products before bloom, when thrips are first seen. Do not apply after plants are in bloom, as these products are toxic to bees.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bull's-Eye Bioinsecticide
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-56872
  • Monterey Garden Insect Spray [Organic]
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-54705
  • This list may not include all products registered for this use.

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Caption: thrips damage on gladiolus
Photo by: R.S. Byther