About spotted wing drosophila
Drosophila flies are sometimes incorrectly called 'fruit flies'. Some people call them 'vinegar' flies because they tend to feed on rotting fruit. There are lots of similar tiny flies here in New Zealand. You'll find them around rotting fruit or your compost heap.
The spotted wing drosophila is not here. It's a menace because it can lay its eggs in fresh fruit, even before they're picked. The eggs hatch into maggots which eat the fruit and cause it to rot. Most other drosophila lay their eggs only in fruit that is already rotting.
These flies are natives of South East Asia. They've recently spread to many other parts of the world, including the Americas and Europe.
Global distribution of spotted wing drosophila
Why they're a problem for NZ
These flies can damage soft fruit, including berries, stonefruit, and grapes. If they get into grapes, the damage they do can taint wine as well as cause crop loss.
If they invaded New Zealand, all commercial and home growers would face increased pest control costs and lowered crop yields.
How it could get here
The spotted wing drosophila is most likely to get to New Zealand in fruit infested with eggs or maggots.
Whenever travelling to New Zealand, always declare any food or fruit in your luggage. If you fail to do so, you could face a $400 fine.
Where would I find it?
It could live in any fruit growing area of New Zealand, from Central Otago to Northland.
How to identify the spotted wing drosophila
It is very hard to distinguish this drosophila from other species in New Zealand. Only experts can tell the females or maggots apart from other vinegar flies.
Adult male flies :
- are about 2mm to 3mm long
- have red eyes and yellow bodies
- have a distinctive spot on the outer edge of their wing.
Signs of infestation
Fruit infested by spotted wing drosophila looks different from normal rotting fruit.
- The skin of the fruit becomes dimpled or wrinkled.
- The fruit rots quickly and collapses around soft spots.
- Uninfested fruit rots more slowly and shrinks over its whole surface, rather than around particular spots.
On close examination, small holes and breathing tubes can sometimes be seen where eggs are laid.
If you see these signs in your soft fruit crops
- photograph them
- capture it (if you can) or put some affected fruit in a sealed bag
- call 0800 80 99 66
Note: This information is a summary of this pest's global distribution and potential impacts to New Zealand.