Agapanthus Gall Midge

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Agapanthus Gall Midge is becoming a more widespread pest that attacks the buds and flowers of Agapanthus. It was originally from South Africa and found in Surrey but is now being found throughout the UK and some parts on Europe.

An understanding of its lifecycle may help with managing the severity of infection: –

Adult midge lay their eggs in spring into emerging buds. The eggs hatch into larvae that burrow into the buds, eating the developing flower, leaving the flowers distorted and damaged. The larvae then fall to the soil where they pupate and hibernate overwinter, emerging again in spring into adults to start the process again. The adult midge can travel in air currents for many miles so may move from garden to garden.

We do not have any proven cures for the problem but a combination of the following may help reduce the population: –

Remove and destroy any damaged flowerheads and buds as soon as possible. Do not put on the compost heap or bonfire where they might survive to another season.

For severe infections it may be worth sacrificing a whole season’s flowers to try and break the cycle.

For plants in pots use a rough top dressing of bark or grit which may make it less attractive for the larvae to move about and pupate in. For established pots trying to remove the top layer of soil and repotting with fresh soil may reduce the population.

Mulch plants in borders with rough/dry material such as bark or shingle.

Place yellow sticky traps amongst your plants in spring to try and catch flying adults to prevent them laying their eggs.

Spray emerging buds with Bug Clear Ultra (non-organic) or SB Invigorator (natural) when you can identify flying adults on your traps in spring. (see image below).

Spray Bug Clear Ultra Vine Weevil Killer in mid-late summer when larvae maybe active in the soil before pupating.

For further information visit https://www.rhs.org.uk/advice/profile?PID=901

From speaking to customers, we know that the infection varies from year to year and does not appear to affect one variety over another, but that the timing of bud development coinciding with when the adults emerge after winter, are likely to be the determining factor.