Latin name: Dasineura tetensi
Plants affected: Blackcurrant
Main symptoms: Small, distorted, crumpled leaves
Caused by: The larvae of a small midge
Timing: Spring and summer
What is blackcurrant gall midge?
Blackcurrant gall midge is a tiny (up to 2mm long) yellowish-brown fly. Feeding by the larvae of this fly causes leaves to become distorted and crumpled.
The females lay eggs between the folds of newly emerged leaves. The eggs hatch a few days later and orange-white larvae feed on the leaf surfaces for 10 to 14 days before going into the soil to pupate. Their feeding prevents normal expansion of the leaves which remain small, distorted and crumpled. On established bushes this is usually not serious although it may be mistaken for the symptoms of reversion disease. Young blackcurrant bushes and cuttings can suffer a check in growth.
There are three generations during the summer with adult flies laying eggs in late April to early June, late June to early July, and late July to August. It is however, the first generation of larvae that is often the most apparent. The third generation of larvae, that finish feeding in August, spend the winter as pupae in the soil.
Check blackcurrants frequently from spring onwards so action can be taken before a damaging population has developed.
- Damage from this midge can often be tolerated as cropping or vigour in home gardens and allotments is rarely affected
- Hoeing the soil under bushes during dry weather in the summer may destroy some of the pupae by exposing them to drying conditions
- Affected leaves can be picked out, although this may cause more damage than the insect
- Some blackcurrant cultivars, such as ‘Ben Connan’ and ‘Ben Sarek’, are resistant to this midge. Removing affected shoots can help reduce infestation levels
- Pesticides available to home gardeners are unlikely to give good control of this insect and are usually unnecessary
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