Daylily gall midge tentatively identified for the first time in Canada
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Name: Contarinia quinquenotata (Loew)
Animalia: Arthropoda: Insecta: Diptera: Cecidomyiidae
Common Names: Hemerocallis gall midge; daylily gall midge
Midge larvae, identified as Contarinia sp., were recovered from Hemerocallis day lilies from a garden center in the greater Vancouver area in the summer of 2001. Based on knowledge about the host association of C. quinquenotata experts consider it highly likely that the larvae examined belong to this species. In addition, various growers have reported Hemerocallis bloom damage typical of C. quinquenotata from a number of sites around Vancouver. However, the identification is still considered "tentative", because no adults were found. CFIA staff will be rearing out the Contarinia larvae to confirm their identity.
Issues of Concern: Daylilies are economically important garden plants. Heavy C. quinquenotata infestations produce flower bud distortions, a failure to open, or even death. Daylily gall midge outbreaks can cause much damage if not controlled promptly and properly. It is estimated that 10 infested buds produce around 3000 flies, and since the female adults are not good fliers, a particular nursery may have very high infestation rates the next year. However, prevention is relatively easy once the signs of infestation are recognized. Abnormally swollen blooms must be broken off early in the season and destroyed by burning or disposing of them with household waste, not through the compost heap.
The midge may move in contaminated soil (over-wintering larvae) and infested buds of the host plant (eggs and larvae).
Hosts: Species of the genus Hemerocallis. Early, yellow-flowered varieties are the most susceptible.
Europe (Austria, Czech Republic, Germany, Hungary, Netherlands, Poland, Slovakia, Sweden, Yugoslavia; United Kingdom)
Infested flower buds become enlarged and distorted. Petals within the buds are abnormally thickened, taking on a dimpled appearance. Affected buds have a large amount of watery liquid between the petals. The larva, a 2-3 mm long legless, white maggot with a dark head capsule, lives in this liquid at the base of the petals. Its cylindrical body is tapered anteriorly and blunt posteriorly. Over 300 larvae may be found per flower bud.
The adult is a ca. 2mm long, grayish-brown fly. The female has a long, retractile, needle-shaped ovipositor. There is one generation per year. Larvae develop inside individual flower buds, which become abnormally swollen if heavily infested. This causes improper opening and, in some cases, a failure to open or even withering and death. After completion of its development, the larva drops to the ground to overwinter in the soil as puparium. Adults emerge from the soil in late spring (May - June), mate and lay eggs in developing flower buds.
The daylily gall midge was reported as a new pest in England in 1989; it was not known to occur in North America prior to 2001.
Source: Canadian Food Inspection Agency
Alford, D.V. 1995. A Color Atlas of Pests of Ornamental Trees, Shrubs, and Flowers. Manson Publishing Ltd., London, England. 448 pp.
Anonymous. 2001. Hemerocallis Gall Midge. The Royal Horticultural Society, Entomology Advisory Leaflet, Number 28. May, 2001. 2pp.
Gagne, R.J. 1989. The Plant Feeding Gall Midges of North America. Cornell University Press. 356 pp.
Halstead, A.J. 1995. The hemerocallis gall midge (Contarinia quinquenotata): where is it now? Cecidology 10: 16-17. CAB Abstract.
Halstead, A.J., and K.M. Harris. 1990. First British record of a gall midge pest of day lily (Hemerocallis fulva L.). British Journal of Entomology and Natural History 3: 1-2
Warning: The information in this archived item was not confirmed with the appropriate National Plant Protection Organization and is provided solely for informational purposes. Please use this information with caution.