Organic Controls for Sciarid Flies

Controlling sciarid flies around houseplants and inside terrariums, on plants grown inside our homes, conservatories, and glasshouses

What are sciarid flies?

Sciarid flies are teeny, tiny flies, from the family Sciaridae, they’re also known as fungus gnats, or by their genera’s scientific names of Bradysia or Lycoriella.  Although sciarid flies live outdoors, as the flies are so minute in size, you’re unlikely to notice these insignificant little flies outside.  Sciarid flies only become a pest indoors, they’re often seen lurking around houseplants, flying slowly near seedlings, cuttings, and glasshouse grown plants.  These same flies can be spotted crawling amongst home-grown mushrooms, or flourishing in the damp, humid environments inside terrariums and indoor gardens.  You might see sciarid flies floating in the air, as they flit around your houseplants, hover around inside your terrariums, or walk or run over the compost, as you move plant pots or seed trays.

I find flies and other insects very interesting indeed, while they’re outside, but I must confess that I find sciarid flies really rather off putting inside.  These irritating flies don’t add anything positive to the ambiance of my home, so I am always keen to prevent sciarid flies from becoming a nuisance.

The lifecycle of the Sciarid fly

Sciarid fly larvae are harder to spot.  The early, larval stages of these flies’ lives are spent as tiny, see-through, dark headed maggots.  They live in composts, soils, and growing mediums; feeding on decaying organic matter, plant root hairs, roots, fungi, soft plant tissue, and algae.  At this stage, you can actually see how full a sciarid fly larvae is, as their transparent appearance provides a window inside their bodies, showing darkened areas where the contents of their stomachs are!

Once they reach maturity, sciarid fly larvae pupate in the soil or compost, where metamorphosis takes place.  They emerge from their pupa as a fully developed fly.  The adult stage of the sciarid fly’s life isn’t lengthy, they live for about a week, at most.  After mating, female sciarid flies lay more than one hundred eggs in the compost or soil, at the base of plant stems, or in amongst plant roots and mushrooms; when the sciarid fly’s life-cycle begins again.

Nemasys® Biological Fruit and Veg Protection contains a mix of different nematodes to treat a variety of plant pests, including: sciarid fly, thrips, as well as carrot root fly, cabbage root fly, leatherjackets, cutworms, onion fly, gooseberry sawfly, codling moth, ants, and caterpillars.

How to control sciarid flies affecting houseplants, terrarium plants, and glasshouse plants and seedlings

The good news is that it is really simple and easy to control sciarid flies.  There’s absolutely no need to resign your houseplants to the compost bin, or banish your fly ridden indoor plants to be shut away inside rooms you don’t use.  I find biological controls provide a simple, quick, and very effective, lasting method of solving any problems with sciarid flies.

I have recently treated all of my houseplants and my terrariums with Nemasys® Biological Fruit and Veg Protection, to eliminate any problems with sciarid flies.  I’ve been so happy with how effective this treatment is, that I wanted to tell you about this pack of biological controls, to help you, if you’re exasperated with sciarid flies inside your home, conservatory, or glasshouse.

Nemasys® Biological Fruit and Veg Protection uses

Nemasys® Biological Fruit and Veg Protection is an ideal, easy to use, and effective treatment for anyone fed up of encountering sciarid flies around their houseplants, terrariums, seed trays, glasshouse and conservatory plants.  This special pack of biological controls is approved for organic gardeners.  These nematodes don’t harm earth worms and they’re safe to use on edible plants (wash your harvest before use).  Packs of Nemasys® Biological Fruit and Veg Protection can be purchased online.

Biological controls

The term ‘biological control’ might sound rather daunting, but don’t be alarmed, it simply means using a natural enemy to control a pest.  Nematodes are natural, living predators, these are tiny, often microscopic creatures.  As they’re both tiny and widespread, it’s hard to say exactly how many types of nematodes exist, as there are likely to be many nematode species that have so far remained undiscovered.

Often you’ll find a single type of nematode are sold in a pack of biological controls.  For example, packs of Nemaslug® Biological Slug Killer contain Phasmarhabditis hermaphrodita, a nematode that preys upon slugs and snails.  What’s even more special about Nemasys® Biological Fruit and Veg Protection is this pack contains different species of nematodes from the genus Steinernema, including Steinernema feltiae and Steinernema carpocapsae.  These nematodes have been especially combined to treat a wide range of pests, found on both plants grown outside in allotments and gardens, as well as on houseplants, glasshouse, and conservatory plants.  This pack can be used to treat and control thrips, cabbage root fly, carrot root fly, onion fly, cutworms, codling moth, gooseberry sawfly, shore fly, and caterpillars, as well as sciarid fly.

Using Nemasys® Biological Fruit and Veg Protection to treat indoor and outdoor pests

If you garden both indoors and outdoors, and you’re dealing with two or more of the pests that this pack of nematodes treats, you could split your Nemasys® Biological Fruit and Veg Protection treatment to target two (or more) different pests on your indoor and outdoor plants.  You could apply half of your pack as a soil drench to treat sciarid flies and the other half as a foliar drench to treat thrips.  However, you’ll need to be certain that you’ve ordered a sufficiently large pack (or packs) of Nemasys® Biological Fruit and Veg Protection to allow you effectively treat all the areas and pests that your plants have encountered.  Ensure that you use your open pack of Nemasys® Biological Fruit and Veg Protection in its entirety, at once – as opened packs and the prepared solution of nematodes diluted with water will not keep for later use – the solution must be applied immediately.

Nemasys® Biological Fruit and Veg Protection can be applied using different methods.  The recommended application method varies depending on the particular pest that you’re targeting and treating.  With this in mind, it’s important to read the instructions on your Nemasys® pack thoroughly, before you begin to prepare your application.

Directions for using Nemasys® Biological Fruit and Veg Protection to control sciarid flies

You can purchase Nemasys® Biological Fruit and Veg Protection online and have a pack sent to your home address (remember to have your pack sent directly to your office, if you’re intending to treat your office plants).  If you’re not able to apply the treatment immediately, when your nematodes arrive in the post, simply pop your pack in the fridge to use later.

Every pack of Nemasys® Biological Fruit and Veg Protection features a ‘use before’ date. It’s best to apply your biological controls as soon as possible after they arrive in the post. Store your pack of Nemasys® Biological Fruit and Veg Protection in the fridge until you’re ready to use it.

Although the nematodes will keep for a few weeks in the fridge, your treatment will be more effective and you’ll get the best value from this product, if you use your biological controls as soon as possible after delivery.  Each pack of nematodes will be marked with a use before date.

This is what the mix of nematodes inside the Nemasys® Biological Fruit and Veg Protection pack looks like. This pack of biological controls is very versatile, it contains a mix of different nematodes and can treat a variety of plant pests, including: sciarid fly, thrips, carrot root fly, cabbage root fly, leatherjackets, cutworms, onion fly, gooseberry sawfly, codling moth, ants, and caterpillars.

Nemasys® kindly gave me this large pack of Nemasys® Biological Fruit and Veg Protection to try out, as I have a lot of houseplants and terrariums to treat.  This pack contains over 10 million nematodes, each pack contains a large enough quantity to fill 8, 5 litre watering can or pump sprayers, to treat an area of 60m/sq.

This is a very easy to use treatment.  I simply followed the instructions on my pack, first mixing a stock solution, using the entire pack of nematodes, mixed with 4 litres of water.  I then enthusiastically stirred this concentrated stock solution, before decanting 0.5 litres of this concentrated, nematode-rich solution, diluting it further by adding 5 litres of water.  I watered this diluted nematode treatment onto my houseplants’ compost, as a soil drench.

If you have fewer houseplants or terrariums, simply use your entire pack of Nemasys® Biological Fruit and Veg Protection in a more concentrated manner.

A closer look at the mix of nematodes inside the Nemasys® Biological Fruit and Veg Protection pack. This pack of biological controls is very versatile, it contains a mix of different nematodes to treat a variety of plant pests, including: sciarid fly, thrips, carrot root fly, cabbage root fly, leatherjackets, cutworms, onion fly, gooseberry sawfly, codling moth, ants, and caterpillars.

Nematodes are very sensitive to light.  To get the best results from your treatment, it’s a good idea to apply your pack of Nemasys® Biological Fruit and Veg Protection on a dull, overcast day, in the early evening, or at night.

My home is shaded, so most of the rooms inside my home are dark.  To get the best results from my Nemasys® Biological Fruit and Veg Protection treatment, I moved all of my houseplants from my brightest room, to my darkest room.  I applied the nematode solution to my houseplants here in this more dimly lit room.  The plants enjoyed the shade in this room for a couple of days, before they were moved back to their usual places.

While, I applied these biological controls to the compost inside my terrariums just as the lights dimmed.

It’s important to water the compost after applying your treatment.

This is one of my Chlorophytum comosum plants – a spider plant. In this photograph, you can see my Chlorophytum comosum plant being treated with Nemasys® Biological Fruit and Veg Protection, to control sciarid flies, which are also known as fungus gnats.
This is one of my Spathiphyllum plants – a Peace Lily. In this photograph, you can see the compost in my Peace Lily’s container being treated with Nemasys® Biological Fruit and Veg Protection, to control sciarid flies, which are also known as fungus gnats.

Once you’ve applied your sciarid fly treatment, the nematodes from your pack of Nemasys® Biological Fruit and Veg Protection will begin hunting the sciarid fly larvae living within the soil or compost they have been watered onto.  These nematodes have a symbiotic relationship with a specific type of bacteria.  Once the nematode has entered the body of a sciarid fly larva, it releases this bacteria, infecting and fatally wounding the sciarid fly larvae.  The sciarid fly larvae will die within a few days of being poisoned.  While this is happening, the nematodes reproduce inside the decomposing body of the sciarid fly larvae.  The nematode’s offspring move on, searching for new sciarid fly larvae to penetrate and reproduce inside, when the cycle begins again…..

This is my Aspidistra. In this photograph, you can see the compost in my Aspidistra elatior’s pot being treated with Nemasys® Biological Fruit and Veg Protection, a natural method of controlling sciarid flies, also known as fungus gnats.
This is my Peperomia polybotrya ‘Raindrop’ plant. In this photograph, you can see the compost in my Peperomia polybotrya ‘Raindrop’ plant’s container being treated with Nemasys® Biological Fruit and Veg Protection, a natural method of controlling sciarid flies, also known as fungus gnats.
This is my Orchidarium. In this photograph, you can see the compost in my Orchidarium being treated with Nemasys® Biological Fruit and Veg Protection, a natural method of controlling sciarid flies, also known as fungus gnats.

How effective are Nemasys® Biological Fruit and Veg Protection for treating sciarid fly – when can you see results?

It’s surprising just how quickly you’ll notice a positive improvement after applying a treatment of Nemasys® Biological Fruit and Veg Protection to control sciarid flies.  Within three days of my application, I saw a marked improvement in the number of flies seen.  The number of sciarid flies inside my home continued to decrease each day, and after a couple of weeks all of the sciarid flies had gone.  Hurrah!

Avoiding sciarid fly in future

The nature and lifecycle of the nematodes inside every pack of Nemasys® Biological Fruit and Veg Protection means that this treatment and control will be somewhat perpetuating and lasting; as these nematodes will continue to reproduce while colonies of sciarid fly larvae remain in your soil or compost.  However, if sciarid flies return, simply apply another treatment of Nemasys® Biological Fruit and Veg Protection.  I applied this biological controls to all of my houseplants and terrariums, on the 9th March 2019.  I’ll let you know when I next need to apply any further treatments.

Update: Have I seen any sciarid flies around my houseplants or inside my terrariums?

May 2019

I applied my Nemasys® Biological Fruit and Veg Protection treatment, on the 9th March 2019.  On the 8th May 2019, I noticed a few sciarid flies inside a number of my terrariums.  I must say that I haven’t seen any sciarid flies around any of my houseplants, as yet.  At the moment, the sciarid flies inside my terrariums are not troublesome.  So, I will leave things as they are for now.  I will update this article, if I notice more sciarid flies inside my terrariums or if I find any sciarid flies around my houseplants, inside my home.

August 2019

I’ve not seen any sciarid flies around any of my houseplants.  I can sometimes see a few sciarid flies inside my Orchidarium and inside a couple of other terrariums.  I’ve not applied any further treatments, since my application on the 9th March 2019.  At the moment I have no plans to apply a treatment of Nemasys® Biological Fruit and Veg Protection, but if I see sciarid flies around my houseplants, I will purchase a treatment right away.

January 2020

I’m now seeing a few sciarid flies flitting around my houseplants.  I’ve not applied another dose of Nemasys® Biological Fruit and Veg Protection, since my initial application on the 9th March 2019, but I’m not ready to apply another treatment.

Houseplant composts

If you’re potting up houseplants, terrariums, or sowing seeds and want to avoid sciarid flies, I’d recommend avoiding the use of peat based composts.  Peat is always very popular with sciarid flies.  These pests can be spread from outdoors to inside, from the use of peat based growing mediums.  This is one of the many ways that sciarid flies manage enter our homes and glasshouses.

There are many effective peat free compost available for houseplants, including coir compost, which can be purchased as a very small, light-weight, dried block, ready to be rehydrated at your convenience.

Here’s a dried block of peat-free coir compost being soaked in water prior to use.
Here’s the same peat-free coir compost, pictured after soaking in a bucket of water.

Visit BASF’s website, for more information on Nemasys® Biological Fruit and Veg Protection.  Always follow the instructions on your pack.

If you’re interested, you can find out how I used biological controls to protect the plants grown for my Tomato Trial from slugs and snails, in this article, here.

Further Trials

You may be interested in some of the other trials I have conducted:

Terrarium, Vivarium, and Orchidarium Trials

To see how my Orchidarium was created, please click here.

To see the design of my Rainforest Terrarium and get lots of tips for setting up a new terrarium, please click here.

To read the first part of my White Orchid BiOrbAir Terrarium Trial, please click here.

To read the first part of my Madagascar BiOrbAir Terrarium Trial, please click here.

To read the first part of my Miniature Orchid BiOrbAir Terrarium Trial, please click here.

To see a planting list of ferns, orchids, and other plants that are perfectly suited to growing inside terrariums and bottle gardens, please click here.

To read about the general care I give to my orchids and terrarium plants, and the general maintenance I give to my BiOrbAir terrariums, please click here.

To read how I track the temperature, humidity, and light conditions inside my terrariums, please click here.

Compost Trial Reports

To see all of my Compost Trials, please click here.

To read advice on planting up containers, please click here.

Scented Daffodil Trial Reports

To see the results of my 2018 Scented Daffodil Trial, please click here.

To read the results of my 2018 Scented Daffodil Container Trial, please click here.

To read the results of my 2017 Scented Daffodil Trial, please click here.

Slug and Snail Trials

To see the results of my Slug and Snail Trial and discover the best methods of protecting your plants from slugs and snails, please click here.

To read about using nematodes to protect your plants from slugs and snails, please click here.

Sweet Pea Trial Reports

To read the results of my 2017 Sweet Pea Trial, please click here.

To read the results of my 2016 Sweet Pea Trial, please click here.

To read the results of my 2015 Sweet Pea Trial, please click here.

Vegetable Trials

To see all of my Vegetable Trials, please click here.

Other articles that may interest you…………

To see articles about edible gardening articles, please click here.

To read about Haxnicks Vigoroot Planters, please click here.

For gardening advice from mid-March to mid-April, please click here.

For gardening advice from mid-April to mid-May, please click here.

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