Who is this?
We all know fruit flies. They like to sit around fruit on the table, especially if it has rotten spots - they particularly like grapes. But they are also attracted to abandoned wine glasses and empty beer bottles.
Not to be confused with dung gnats, which tend to move by crawling, and fungus gnats, which are more dainty and fly around more scattered. You can find the information for both in the dung gnat instructions .
Fruit flies like the same nutritious material as the worms. In the worm composter, as long as the worms follow and the composter is in balance, you will never encounter the same number of fruit flies that you encounter in the organic waste bin or in the garbage bag - because the worms eat the food out of their noses. Of course, fruit flies are also part of the composting system and do not harm the composter, and a few individual fruit flies do not bother you either. When they occur en masse, however, they are uncomfortable and indicate that something is wrong.
Cause : An invasion of fruit flies indicates that your composter is out of balance. The most common cause is that the worms aren't coming up with food and therefore the flies have an advantage - the easiest is to find the source and fix it.
First fix the cause
- Check the grids: is there contact everywhere so that the worms can get up and down easily? If necessary, remove the grid again and mix everything. You can find an example of this situation in our field report (link).
- Control the amount of food: remove what is too much (if it stinks or has gotten warm) and bury the waste, for example in a large flower pot.
- Mix in the fresh scraps with pieces of dry cardboard or other woody material.
- Air/mix the composter on the balcony so that the adult flies escape (although that's a bit awkward at the moment ;) ).
- Sprinkle the surface of the composter with a 1-2 cm layer of soil.
- Reduce the amount of food or pause completely until everything has calmed down.
Traps and preventive measures
- Trap 1 : Put a piece of fruit in a glass and stretch cling film over it. Then you make a single small hole in the foil and the flies can't find their way out. Release the flies outside and remember to replace the piece of fruit regularly (bury it in a flower pot outside).
- Trap 2: Fill a glass with vinegar (attracts the fruit flies) and a squirt of dish soap (lowers surface tension), the flies drown in it.
Preventive Measures
- Dig fresh fruit waste lightly into the composter at a time. Alternatively, you can occasionally cover the layer of fresh waste directly with dry soil (clay garden soil or old flower potting soil is best). Scraps of paper or other dry material are also suitable.
- Take a break from feeding from time to time, being extra careful after the trellis set in.
- Cover the lining layer with rock flour or our Mineral Mix. This binds the odors that are tempting for fruit flies.