Tiny little flies in the flower pot: what to do?

Small flies in the flower pot are annoying and a danger to the plant. Fighting them is easy, but the larvae are not so easy to get rid of. But some measures promise success.

Which pest is it?

The tiny little flies in the flower pot are mostly mourning flies , also known as fungus gnats. In fact, they are not a fly but a species of mosquito with the scientific name Sciaridae. These features are typical of tiny weeping flies and their larvae:

  • hatched fungus gnats are 1-7 mm in size
  • their body is slender and dark in color
  • they have long legs and antennae on their heads
  • male animals have dark wings
  • female animals are wingless
  • Fungus gnats don’t have a stinger
  • the 5-10 mm larvae live in the potting soil
  • her white-glassy body is slender, the head capsule black
Tip: shake the plant a little or move the flower pot. The flies will immediately rise and buzz around the plant. If they fly back and forth, you can be sure that they are fungus gnats.

Damage to the plant

The tiny little flies in the flower pot do not contrast with the potting soil due to their dark colour. Because of this, their appearance is rarely noticed early. Since each fly can lay around 200 eggs in its lifespan of around five days, the conquest of the plant is progressing at a rapid pace.

  • Young plants suffer more
  • it shows a stunted growth
  • Seedlings die
  • fungal infection occurs (as a secondary disease)

Start fighting immediately

As soon as you have discovered tiny little flies in the flower pot and identified them as fungus gnats, there is no time to waste. Some possible measures are listed below. They can and should be used in combination to complete the fight faster or to catch both flies and larvae.

home remedies

  1. baking powder

Baking powder is always in the house, is inexpensive and does not harm the plants. Sprinkle the substrate in the flower pot with the powder and then moisten it with a spray bottle. The larvae of the Sciaridae will feed on it and die. If the infestation is severe, you should repeat the process at regular intervals.

  1. matches

Matches are one of the measures that our grandmothers took against fungus gnats. Depending on the size of the flower pot, stick one or more matches into the ground with the colored head. This contains potassium chlorate, which dissolves and goes into the soil. This is how it reaches and kills the larvae. However, this household remedy is only suitable for less sensitive plants.

Tip: Light a match near the plant. The smell will drive away the winged males and keep them away from the flowerpot for a while. This is how you ensure a mating break.
  1. vinegar and dish soap

Mix equal parts water, vinegar and dish soap. Fill a bowl with it and place it near the affected plant. The smell of vinegar attracts small fungus gnats, detergent destroys the surface tension of the water so that the animals drown.

  1. yellow board

The panels, which are covered with an adhesive film, magically attract small fungus gnats with their yellow colour. If the infestation is severe, however, it may be necessary to set up several yellow boards or replace them with new ones every few days. Additionally, you should take other measures to control the larvae.

Tip: Sticky traps are available cheaply in a garden center, hardware store or inexpensively in an online shop.

mechanical methods

  1. cover

Anything that can stop the adult fungus gnats from laying their eggs in the top layer of potting soil will help reduce the population.

  • Cover the potting soil with 1-2 cm of quartz sand
  • alternatively with gravel or lime
  • dried coffee grounds also work well
  • or put the pot in a nylon stocking for 3-5 weeks
  • be sure to tie it up
Note: If the current weather and location allow, refrain from watering for a few days. This allows the surface of the earth to dry several centimeters deep. As a result, it loses its attractiveness as an egg-laying place, because fungus gnats like moisture.
  1. Commercially available pesticides

Means that are used against mosquitoes in the pond are also effective here. They are administered via the irrigation water. There are now ecologically compatible products that are produced on a biological basis. Ask about it in retail.

  1. repot

If a plant is heavily infested, a full soil swap can take the pressure off it.

  • pot the plant
  • Rinse the root ball and free it from all soil residue
  • Place old soil in a bag and seal tightly
  • take it outside immediately and dispose of it in a trash can
  • Thoroughly clean the old pot or use a new pot
  • Plant in new soil
  • if necessary, it is also sufficient to replace the top layer of earth
Tip: If you don’t have new soil on hand, you can put the old soil in a glass jar and sterilize it in the microwave for a few minutes.

herbs

  1. Parsely

Fresh parsley gives off a scent that adult fungus gnats dislike. You can take advantage of this to prevent egg laying.

  • Chop the parsley very finely
  • Scatter evenly over the potting soil
  • the effect wears off as it dries up
  • sprinkle new parsley in good time
  1. chives

Tiny little mosquitoes give chives a wide berth. Its essential oils smell so intense that just being near the plant is enough. The green tubes do not have to be cut up first. This plant is therefore ideal for controlling mosquitoes in a greenhouse as it becomes even more fragrant in the heat. Place one or more flower pots near threatened plants and the flies have no choice but to flee.

  1. Neemöl

The oil obtained from the seeds of the neem tree (also known as the neem tree) prevents the larvae from forming the vital chitin.

  • Mix neem oil with water (1:100)
  • Add soap nut powder as an emulsifier
  • Shake the emulsion vigorously
  • spray on the potting soil

predators

  1. nematodes

The tiny roundworms are benign parasites. They ignore the plant and only hunt the larvae. You can get nematodes in specialist shops or on the Internet. They are put into the soil via the irrigation water, where they continue to multiply. This ensures that even the last pest is eliminated over time.

  1. bacteria

A bacterium called Bacillus thuringiensis var. israelensis (BTI) is also commercially available. It also gets into the flowerpot with the watering water, where it forms permanent spores with protein crystals. These are absolutely harmless for the plant, but highly toxic for the larvae of the fungus gnat.

  1. Raubmilben – Hypoaspis miles

Another beneficial creature hunts the hidden larvae for us. Their use is ideal for closed rooms such as conservatories or greenhouses. A few weeks after the last larva has been consumed, the predatory mites simply die out without leaving any unpleasant traces of their presence.

Prevent fungus gnats

Mourning flies are dragged into the house with newly purchased plants. The soil used for planting or repotting can also be contaminated with mosquito eggs. You can do this:

  • Examine plant balls more closely before buying
  • also keep an eye on it for several days at home
  • expensive quality soil is less polluted
  • Always sterilize soil before use
  • in the oven or microwave

Also, avoid keeping your plants too wet. Let the soil dry before you reach for the watering can again.

frequently asked Questions

In principle it is possible. But here there is a risk that parts of the plant will also be sucked into the suction and damaged. If you use this measure, approach the plant carefully. Don’t forget to fight the larvae as well!

Even plants on the balcony are not spared by fungus gnats. But we are less aware of their presence outdoors than in a closed room. They should also be combated outdoors because sooner or later they will impair the vitality of the plant.

Fruit flies are brown and thicker than mourning flies, their legs are shorter, and they don’t have long fillers. Your whereabouts are also the clearest clue. While the mourning flies can be found in the flower pot, fruit flies buzz near ripe or rotting fruit.

Kira Bellingham

I'm a homes writer and editor with more than 20 years' experience in publishing. I have worked across many titles, including Ideal Home and, of course, Homes & Gardens. My day job is as Chief Group Sub Editor across the homes and interiors titles in the group. This has given me broad experience in interiors advice on just about every subject. I'm obsessed with interiors and delighted to be part of the Homes & Gardens team.

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