Contarinia quinquenotata

Contarinia quinquenotata is a small midge which infests the flower buds of Hemerocallis species, cultivars, and mature unnamed seedlings, causing the buds to remain closed and rot.[2] It is a pest within the horticultural trade in several parts of the world.[3] It is known by the common names of daylily gall midge and hemerocallis gall midge.[4]

Contarina quinquenotata
Damage to the bud of a Hemerocallis flower from larvae of C. quinquenotata
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Diptera
Family:
Cecidomyiidae
Genus:
Contarinia
Species:
C. quinquenotata
Binomial name
Contarinia quinquenotata
Loew 1888[1]

Description

Adults are tiny greyish-brown alate midges about 2 mm long. Females deposit their eggs with their long, penetrating ovipositors into developing Hemerocallis flower buds during May through early July. This fly is difficult to see when it is flying.[5]

Life cycle

This fly is univoltine, having only one annual cycle. It mates shortly after emerging from its overwintering puparium. Females lay eggs inside developing Hemerocallis buds which hatch into 2-mm-long, elongate, legless white larvae. Their presence and feeding causes distortion of bud tissues and failure of buds to open. Infested buds characteristically become more globular than normal, elongate Hemerocallis buds, tepals within buds become thickened, and a watery liquid is present between the tepals in which the larvae live. A few through hundreds of larvae live within a single bud. Larvae emerge from disfigured buds and to the soil in which they pupate, spend the winter as pupae, and emerge as adults in the following spring.[5]

Buds of a Hemerocallis cultivar with a short globular bud (lower left) distorted by infestation of the hemerocallis gall midge, compared with normal cylindrical bud at centre

Distribution

Cotarinia quinquenotata probably originated in Asia where wild Hemerocallis are native.[5] It occurs only in gardens or plant nurseries which contain Hemerocallis.[5] The midge has been slowly spreading across the world in infested Hemerocallis plants and soil. This fly was first noted in the United Kingdom in 1989 and has now spread to many parts of the United Kingdom.[5] It was first reported in Canada in 2001 and has spread into the USA.[6]

The spread is assumed to occur from larvae within buds of imported plants or the soil in plant containers.[5]

Commercial impact

Devaluation of infested plants by their failure to produce the attractive flowers favoured by gardeners for their colourful displays. Plants can safely be shipped only without their flower scapes, flower buds, and flowers and with bare roots.[5] The need to control the midge by whatever means increases the cost of producing Hemerocallis plants.

References
  1. Contarina quinquenotata, Encyclopedia of Life, retrieved 13 June 2014
  2. "Hemerocallis Gall Midge". American Hemerocallis Society. Retrieved June 12, 2014.
  3. "Continaria quinquenotata". Phytosanitary Alert System. North American Plant Protection Organization. 2014. Retrieved 12 June 2014.
  4. Hemerocallis gall midge, Royal Horticultural Society, 2014
  5. McLean, Ian (20 Aug 2011). "Contarinia quinquenotata". GB Non-natives Fact Sheet Editor. GB Non-natives species secretariat. Retrieved 13 June 2014.
  6. "Continaria quinquenotata". Invasive species - Invertebrates. Encyclopedia of Puget Sound. 2014. Retrieved 12 June 2014.
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