How to recognise it
The larvae are white (almost transparent) maggot-like creatures which are up to 3mm long. If you open up a distorted bud you’ll find them crawling around in a watery liquid. Over 300 larvae can be growing in a single bud.
Adult midges emerge from the soil from May and fly up to the flower buds to lay eggs. The larvae develop within the buds and feed on them, causing distortions. They then fall to the soil to overwinter inside silk cocoons.
Why it’s a problem
The infestation can cuase flower buds to swell and distort, then fail to open. They may dry up or rot.
Where you are likely to find it
It affects Hemerocallis (daylily) plants. Yellow flowered varieties are worse affectd. Damage occurs throughout the summer but tends to peak in June, declining through July.
How to deter it
Plant later flowering varieties – most of their buds won’t have formed during the gall midge’s egg laying period so they should avoid an infestation.
How to get rid of it
Pick off and destroy any affected buds as soon as you notice them. You may also find it helps to spray the affected plants with an appropriate systemic insecticide when the adults emerge in May and June, but the timing must be right to kill them before they lay their eggs.
Avoid spraying opened flowers as the larvae are unlikely to be on them and you could instead kill beneficial pollinating insects.
Do not compost affected buds as the larvae will simply overwinter in the compost and appear again the following year.
Is it good for anything?!