Garden pest identification. Daylily Hemerocallis gall midge.

Garden pest, Hemerocallis gall midge

Hemerocallis gall midge infestation

Day lilies – Hemerocallis species and cultivars have a parasitic pest called the Gall midge Contarinia quinquenotata

It’s been gradually spreading through the UK since 1989.

There is no control for the pest other than picking off the infected flower buds and destroying them.

Don’t put them in the compost bin as they will pupate and emerge next year.

Daylilies Hemerocallis gall midge pest I put the infected buds on a table in the sun thinking that this would kill the larvae but instead the maggots wriggled out and went into early pupation.

Garden pest, Hemerocallis gall midge

 Burning the buds is the sure way of destroying these maggots. 

 Contarinia quinquenotata

The adult fly is tiny and lays hundreds of eggs in the developing flower buds.  The white maggots grow to about 2-3mm. When ready to pupate the larvae crawl out of the flower bud and fall to the ground where they bury themselves in the soil, pupate, then emerge as adults flies the following year.

Photography By Neil Bromhall Complete Gardens Advice CD-ROM Ltd

4 Responses to Garden pest identification. Daylily Hemerocallis gall midge.

  1. Some of my day lily buds are not opening, they seem to look damp and partly translucent. I have had gall midge and have been frantrically picking off the buds. This seems to be something differant. Any ideas on what it maybe?. I hope it’s not a virus. Thank you

  2. charlotte fanders, cph says:

    I have just had a customer looking for “fine netting” to cover her daylilies to protect them from this fly.
    She indicated that they have newly arrived from Canada. (I live in Washington State)
    I suspect that what she wanted was (possibly floating row cover rather than netting)
    As I work for a “big box store” it seems to me that
    we should be knowledgeble of such possible problems since we guarantee the plants for a year so it they fail we have to “buy them back”.
    Any other ideas on control?
    Charlotte Fanders, CPH

  3. An enduring gardener says:

    I would like to know if proactive applied NEMATODES would help with Midge larval issues over the duration–if indeed the larvae drop and eventually submerge subterreaneally, would not progressive nematode application/spray-in help with this problem eventually? Would the nematodes not destroy them?

    • An enduring gardener says:

      Hi, it may be a fungal issue (leaf/stem/bud surface) or, possibly other issues going on beneath the soil (larval, etc).

      Try a succession of fungal treatment spray (copper, etc) and if there isn’t any progressive results, then I would consider carefully digging up the plant and combing through to see if there is tunneling/burrowing or related damage to the to the roots and/or RHIZOMATOUS mass.

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