the essentials in brief
- Cherry vinegar flies lay their eggs on soft-skinned berry fruits that are ripe. The smell of rotten fruit is attractive.
- Damage is caused by sap leakage and larval development. Consequential damage can result from fungi and pests. There is no health risk for humans.
- Cherry vinegar flies can be recognized by their red eyes. Males have dark spots on their wing tips. Females have a conspicuous laying apparatus.
- An infestation can be prevented by protective nets or clay. Preventive measures such as fruit selection, early harvest and regular mowing are important.
What damage do cherry vinegar flies do?
Females of the cherry vinegar flies lay their eggs through the sawn-up shell into the pulp of previously undamaged fruits. This distinguishes the species from the native vinegar fly, which prefers to fly to overripe fruit. With bare
eye it is not possible to tell whether eggs have been laid on a fruit. Research has shown that the Cherry vinegar fly does not transfer vinegar bacteria to the fruit. But consequential damage is possible through the open fruit skin:- Secondary pests find access
- The larvae's feeding activity causes sap to escape, which attracts pests
- Juice residues provide a breeding ground for putrefactive fungi
- Crop losses in terms of quantity and quality
also read
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- When maggots live in cherries
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Digression
Egg laying
If a female has laid her eggs on a fruit, she marks this area. This prevents other females from laying their eggs in the immediate vicinity. Mild temperatures and sufficiently high humidity ensure that a maggot hatches out of the egg.
Damage potential
The black-bellied fruit fly (pictured here) does more damage than the cherry vinegar fly
The cherry vinegar fly (Drosophila suzukii), which originally comes from Asia, was observed in Germany for the first time in 2011. In the following three years, the pest spread across the country. The species is favored by the increasingly mild climate. If the temperatures in winter fall into the minus range and rise sharply in summer, the populations automatically decrease. Observations of the infestation have shown in recent years that the damage potential of the Cherry vinegar fly in viticulture is less than the damage caused by the black-bellied fruit fly (Drosophila melanogaster).
Cherry vinegar flies can cause damage in viticulture and fruit crops. Areas that are particularly at risk are close to forests and tall meadows.
Dangerous for people?
If you are unsure whether the infected fruits are still edible, you should trust your senses. Look closely at the fruit and smell it. If you don't smell any unpleasant smells, try the pulp. Even freshly infested fruits containing eggs or newly hatched larvae are harmless and not harmful to health. In the late infestation stage, injuries with juice leakage are clearly visible and the fruit gives off a vinegar odor. Such fruits are inedible.
Dealing with the harvest if there is a suspicion of infestation:
- harvest only apparently intact fruits
- Harvest right at the beginning of fruit ripening
- Stop egg development by cooling the harvest strongly
- Heat the pulp or soak in alcohol
Even fruits that have been infected by larvae can usually still be eaten
Recognize cherry vinegar flies
At first glance, the Japanese cherry vinegar fly looks like native species. It has a yellow to brown colored body and dark stripes on the belly. Cherry vinegar flies appear lighter than fruit flies. The red eyes are noticeable. The larvae are white in color and cylindrical in shape. They reach a size of 3.5 millimeters. While females differ from other species in their laying apparatus, males have one striking feature:
| male | female | |
|---|---|---|
| size | 2.6 to 2.8 millimeters | up to 3.4 millimeters |
| wing | each wing tip with a dark spot | transparent |
| Abdomen | nondescript | sharply toothed egg-laying apparatus |
Fight cherry vinegar flies
The Asian cherry vinegar fly can be controlled with insecticides. But in the private sector, chemical agents are no solution. With suitable alternatives, you can fight off the fruit pest biologically without endangering your health.
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Build a trap yourself
Traps are easy to make yourself from recycled plastic cups with lids. A disposable cup for smoothies or other drinks with a capacity of 500 milliliters is ideal. Although they are not sufficient to completely combat the infestation, they can be used for control.
Crafting instructions:
- Poke three to four millimeter holes in the lid
- Mix apple cider vinegar and water (1: 1) and pour into the beaker at a height of four centimeters
- Add drops of detergent
- Hang the trap in the shade at the level of the fruit
- Use cable ties for fastening
A placement as early as possible before the fruit ripens is necessary in order to determine the infestation in good time. Drosophila species get into the trap through the small openings, while unwanted secondary catches by larger insects are prevented. Prepare a double trap set so that you can easily swap out the containers and then replace them.
kaolin
Kaolin is better known as china clay or white clay. The main component is kaolinite, which from a chemical point of view is an aluminum salt of silicic acid. The finely ground powder, dissolved in water, keeps cherry vinegar flies from laying eggs after at least four injections. The effect lasts until the next rain. If the flies are dusted with the agent, the fine particles adhere to the body and trigger an excessive need to clean. The flies forget to eat and neglect to reproduce.
Advantages:
- Bless you: no danger to humans or pets
- biodiversity: no killing effect, only a deterrent effect
- effectiveness: uniform particles form an evenly dense spray coating
Networks
Fine-meshed nets keep the cherry vinegar fly away from the fruit
Safety nets are ideal for private use if you want to protect isolated shrubs from being attacked by the cherry vinegar fly. It is important that the net has a maximum mesh size of 1.2 millimeters and is hung completely over the bush. Even the smallest gap allows access. The disadvantage of this variant is that flies can get to the bush by opening the nets. Therefore, only open the covers on hot and dry days when there are no cherry vinegar flies in the air.
Tips
In order to increase the protection against the influx of cherry vinegar flies, you should cultivate the covered shrubs in the greenhouse if possible.
Preventive measures
If possible, you should moderately defoliate the affected fruit bushes. In this way, the trees are better ventilated and more sunlight falls into the interior. Cherry vinegar flies find dry and heavily sunlit shrubs less attractive. The surrounding vegetation should also be kept as low as possible if there is a suspicion of infestation in order to favor warm and dry conditions.
What you can do:
- Thin out fruits before ripening and remove damaged fruit
- do not leave any windfalls as the smell attracts cherry vinegar flies
- floor mulch to accelerate rotting processes
Tips
To determine an infestation, you can store fruit in a close-meshed mesh bag and observe it over the next few days. In warm temperatures, the flies hatch within a short time.
Which plants attack cherry vinegar flies?
Drosphila suzukii is not picky about the host plants. Females prefer to lay their eggs on soft-skinned fruits. Red grape varieties with a compact structure and thin skin, as well as cherries, are particularly attractive. Because of the strong increase in the summer months, late-ripening fruit varieties are also endangered. The cherry vinegar fly also attacks wild berry bushes such as raspberries and blackberries. Apples and pears are only attacked when the peel is already damaged.
frequently asked Questions
Does fruit lime help against the cherry vinegar fly?
Fruit lime is ineffective against the cherry vinegar fly
Fruit lime is a milk of lime that is used as a white paint for fruit trees. It contains slaked lime and helps against fungal diseases. No effect could be found in the control of cherry vinegar flies. Glued color panels and products with lavender oil are equally ineffective.
What does the infestation look like in raspberries and blackberries?
As part of a research project by the Bavarian State Ministry for Food, Agriculture and Forests (StMELF) it was determined at which stage of ripeness cherry vinegar flies prefer their eggs to raspberries and blackberries dropped.
While no eggs were found in unripe blackberries with a slight red colouration, almost all samples of raspberries with incipient red colouration were infested. The redder the blackberries got, the more eggs there were in the pulp. The number of eggs in ripening raspberries, on the other hand, decreased slightly. In both cases, the females preferred to seek out fruits that were fully ripe.
Can I see an infestation by the cherry vinegar fly early?
It is difficult to spot an infestation in time. It cannot be seen with the naked eye whether there are eggs in the pulp. Only the presence of dolls can be determined through a magnifying glass. The pupae have two appendages that protrude from the peel of the fruit. Typical for the pupae of the cherry vinegar fly are star-shaped appendages, which do not occur in pupae of related species.
How do cherry vinegar flies live?
The species prefers mild temperatures and moderate conditions. If the thermometer rises above 30 degrees, the activity of the insects is restricted. At more than 32 degrees, no more reproduction takes place. Adult flies survive winter in a frost-free hiding place. You wake up in spring when the temperature rises to ten degrees. Due to these demands, the species was able to spread over large parts of Europe.
