Daylily: Daylily gall midge
categories: Bulbs Daylily Daylily Insects Ornamentals
revision date: 2023-02-07 12:00
Photo by: D. Pehling
Biology
The daylily or Hemerocallis gall midge (Contarinia quinquenotata) is the larva of a small, nondescript, grayish-brown fly. The adult fly overwinters in the soil and emerges in spring to lay eggs on developing flower buds, making early-blooming varieties most susceptible to damage. There is only one generation per year, so later-blooming varieties are less likely to be infested. The eggs hatch in mid-spring to early summer. Up to 300 larvae may feed inside a single flower bud. The legless and wingless larvae are white to cream-colored, and about 1⁄8″ long. Damaged buds appear unusually short, swollen, and distorted. They may also be discolored or pale. Buds may either open abnormally or fail to open and drop from the plant. The larvae may be confused with thrips.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Avoid early-blooming daylily varieties, particularly early-flowering yellow types.
- Plant late-blooming daylilies, which are less susceptible to damage.
- Monitor plants for distorted, dimpled buds with thickened petals and watery fluid within the buds.
- Remove infested buds. Destroy infested buds or dispose of them in a sealed container. Do not compost infested plant material.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
If gall midge is a problem in your area, apply as flower buds of early varieties develop in order to kill egg-laying female flies. Avoid spraying blooming plants as most of these products are toxic to bees. Contact (non-systemic) insecticides may have limited efficacy as adults may fly and lay eggs over a period of several weeks.
Approved Pesticides
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.