Fighting flies in the potting soil: 7 home remedies for fungus gnats

The flower pot is not only a suitable habitat for many plants, but also a breeding ground for numerous pests that like to attack the plants. As soon as a swarm of small, black flies rise from the pot during watering, they have the larvae of the sciarid gnats nestle in the potting soil and happily eat the fine roots. The right care and suitable home remedies work wonders against the robust pests.

Sciarid gnats

What are fungus gnats?

The sciarid gnats (Sciaridae) are a family of mosquitoes that live in Europe with over 600 species occur and, unlike their relatives, the mosquitoes, are not interested in human blood. They can be recognized by their slim build and their deep black color, even if there are a few exceptions. On average, they grow to be between one and seven millimeters, so tiny to the naked eye. Despite their small size and short lifespan of a maximum of five days, they do cause great damage, as the females can lay over 300 eggs in the potting soil.

• Sciarid fly larvae have an easily recognizable, glassy-gray body of 5 - 10 mm
• feed on rotting plant tissue and fresh, fine roots
• remain in the flower pot for about 20 days until further development
• The pupa is yellow-brownish
• Males have wings, females do not

After the flies have passed their pupa status, they reproduce and the whole cycle starts all over again. If you are not sure whether the flies in the potting compost are fungus gnats, watch out for the following behaviors.

• Prancing, slightly "swaying" flight movements
• Larvae and pupae can be found in or on the surface of the substrate and are easy to recognize due to their different colors
• stay only near plants or compost

They are often confused with fruit flies, which however have a brown instead of black body and, according to their name, stay near ripe fruit. So if there is a swarm of brown flies near your fruit basket, they are not sciarid gnats.

Symptoms

Symptoms of Sciaridae infestation

If you want to fight the flies, you have to check beforehand whether they really are infested with them. Due to their function as a destructor, an organism that decomposes plant materials, they are the most important representatives of this function in nature, alongside the fungi. Especially in the forest, you help to decompose the rotting parts of the plant on the forest floor. They are extremely successful with it, but this has a negative effect on the keeping of house and greenhouse plants, as they simply multiply too quickly.

Infested plants show the following characteristics:

• Seedlings and cuttings die
• poor growth, plants wither
• hollow stems due to insect damage
• many mosquitoes fly around the plant

Note: Young plants in particular suffer greatly from the mosquito's hunger and can pass within a short time, which is what makes the infestation so dangerous. It is more advantageous if you do not even give the insects the opportunity to use your plants than Choosing a feast, because with the right prevention the mosquitoes will become the basis of their food withdrawn.

prevention

Preventing fungus gnats

In order to control Sciaridae species effectively, it is important not to provide them with an egg-laying base. The most important thing here is the plant substrate, because the larvae need permanently moist soil in order to be able to develop. Therefore, here's what you should do to prevent oviposition.

• only water when the surface of the potting soil is dry
• water over the saucer for plants that are thirsty for water
• If there is water in the saucer, let it stand for about 20 minutes and then pour it away
• cover the surface with a layer of quartz sand that is less than two centimeters;
• Quartz sand removes moisture from the earth and prevents eggs from being laid because the surface is closed but breathable
• if possible, switch to hydroponics or special substrates that do not require soil

These points can save you a lot of work, because as long as the potting soil can breathe and not get too moist, the healthier your plants will stay. It is particularly important that there is no waterlogging, as this increases the pests' reproduction process. It is always a good idea to let the surface of the potting soil dry out in the flower pot. Purchased potting soil is often to blame for the infestation, especially organic and humus substrates, as these represent the perfect breeding ground for sciarid gnats.

Here are a few things to look for in purchasing the Earth:

• Store purchased potting soil in a cool, dry place
• keep the container closed
• cover it with a tarpaulin if necessary to contain the infestation

So the flies have no chance of getting closer to the earth and laying their eggs in it. However, it can happen that eggs are already present in many substrates, as these are found in masses in peat and are therefore included in a large part of the soil available. For this reason, it is important to sterilize soil before use, especially if it is a humus-rich substrate from organic production.

You only need an oven to sterilize the potting soil:

• preheat the oven to 85 ° C
• Spread the earth out on a baking sheet and loosen it up a little
• put the tray in the oven for 30 minutes
• then you can use the substrate without hesitation

It is also advisable to check whether there are eggs in the soil before sterilizing it. For this you need a yellow sticker, a kind of sign in a yellow shade that has adhesive surfaces. The color magically attracts the mosquitoes and they then stick to the sticker.

Test the potting soil as follows:

• take a sample of the freshly acquired soil
• place them in a small flower pot together with the yellow sticker
• moisten them heavily
• place a close-meshed net with a maximum mesh size of one millimeter around the pot
• wait three weeks

If the earth is already interspersed with eggs, there should be numerous mosquitoes on the yellow sticker after the waiting time. Thanks to the close-knit network, these cannot escape and do not infect other plants. If flies have been discovered, the substrate must be sterilized. Soil for indoor plants makes sense because it has already been sterilized in advance.

Tip: As an alternative to the oven, you can also heat the earth for 30 seconds in the microwave. That works just as effectively.

Effective home remedies

You don't always need chemistry to control the flies in the substrate. The chemical club can damage your health, as the insecticides can also reach humans and pets. In addition to the classic yellow boards or stickers, you should use the following home remedies when fighting the annoying insects.

• baking powder
• matches
• parsley
• chives
• Beneficial insects
• Neem oil
• vinegar

Tip: Coffee grounds, along with alcohol and nicotine, are a commonly recommended means of combating sciarid gnats, but the coffee grounds are only marginally effective. Due to the structure of the coffee grounds, over time the soil is too strongly absorbed and begins to condense and mold, which is not ideal in the fight against pests.

baking powder

Baking soda is an effective means of combating flies. Since this is not a chemical, you can actually use the product on all plants without having to take any health risks. For this you only need baking powder and a little patience, because even if the first application does not work with the product, the second application will be more effective.

Proceed as follows:

• sprinkle the substrate with the powder
• use a spray bottle to moisten it
• then the powder is absorbed into the earth

After the powder is absorbed, the larvae will eat it and die on the ingredients. Depending on the severity of the infestation, the treatment may take a while, but due to the low cost you can get a large amount of the powder for a few euros. The motto here when fighting the flies is hold out and you should renew the powder at regular intervals.

matches

Matches are effective at fighting those pesky flies. They contain potassium chlorate in the heads, which is extremely aggressive on the larvae. The matches can also be used to drive away the adult males by lighting a match near the plant. The smell drives them away and they avoid the plant for a while. To fight the larvae with the woods, you just have to stick your head in the ground and wait. The potassium chlorate moves into the potting soil and gradually kills the larvae. This method is not suitable for sensitive plants, as excessive amounts of potassium chlorate could damage them.

parsley

Parsley is a popular culinary herb and, surprisingly, can be used to fight the sciarid gnats. All you need is fresh parsley, which you cut into small pieces and spread over the surface of the potting soil. Because of the essential oils it contains, the adult mosquitoes in particular avoid the equipped plant and thus do not produce any offspring. Here you just have to make sure that the effect diminishes as the scattered parsley dries up and you have to sprinkle it again and again. So get yourself an ample supply of the herb.

chives

Chives work like parsley for combating, but are better suited for plants that are in flower pots in the greenhouse. Since different temperatures apply in the greenhouse, the essential oils and ingredients work better here and protect the potting soil more effectively from the pests. However, this is not cut into small pieces, but placed in close proximity to the infested plants or in large numbers in order to drive away the insects with their smell. In this state, chives always grow back and you not only fight the flies, but you can also enjoy the herb in terms of taste.

Beneficial insects

Appropriate beneficial insects can be used to combat the fungus gnats, targeting the larvae and killing them. They include those listed below.

• Roundworms (nematodes) Steinernema feltiae: works between 12 ° C and 30 ° C within three weeks
• Bacillus thuringienses bacterium: works at any temperature within a few days

While the nematodes are active and literally chase the larvae of the sciarid gnats, they spread the bacteria via spores inside the pot and produce proteins that are toxic to the flies. The nematodes, on the other hand, feed on the body fluids of the larvae and, as a result, they die. Both beneficial insects are biologically and ecologically harmless and have no influence on people, animals or the plants themselves. Both beneficial insects even multiply and provide long-term protection for the potting soil. They are administered through the irrigation water.

Neem oil

The oil from the neem tree, more precisely the seeds, acts as a natural poison against the formation of chitin in the larvae. The reason for this is the contained substance azadirachtin, which has a negative effect on the hormonal balance of the sciarid gnats.

The oil is used as follows:

• mix the oil with pouring water in a ratio of 1: 100
• add soapnut powder
• shake the emulsion vigorously
• use the home remedy as irrigation water or via a spray bottle

vinegar

Place a bowl filled with vinegar, water and washing-up liquid at a dosage of 1: 1: 1 next to infested plants. Flies are attracted to the vinegar smell and die due to the surface tension released by the detergent. You will eventually drown.