Affiliate Disclaimer: As an Amazon Associate I earn from qualifying purchases.
Whether all year round, or just over winter, chilli plants will happily grow indoors if the conditions are right.
I have recently moved my chilli plant indoors now that the UK winter is approaching in an effort to extend the fruiting season and ensure a supply of freshly grown chillis all year round. In doing this, I have come across an unexpected problem: I started to notice the presence of lots of tiny black flies all around the plant.
I first noticed the flies about a week after moving my chilli plant indoors. And to make matters worse, they started to migrate all around the house and I began to find them in multiple rooms!
Indoor chilli plants can attract flies. Sciarid flies, also known as house plant flies or fungus gnats, are a common problem, and reproduce by laying eggs in the compost of the plant.
Where do Flies on Chilli Plants Come From?
After investigation, I found that the flies I was seeing were actually originating from the compost of my chilli plant rather than the plant itself. Just shaking or lightly disturbing the plant and pot would result in a swarm of flies on both the surface of the compost and around the plant itself – not good!
What are These Flies Called?
The flies that I was seeing were called Sciarid Flies, also known as house plant flies or fungus gnats. They can thrive throughout the year in the warm, moist conditions provided by many a houseplant compost. Once established, their numbers can increase very quickly.
How do I Identify Sciarid Flies / Fungus Gnats / House Plant Flies?
Fungus gnats are black / brown in colour grow to around 3-4mm in length. They have 2 antennae and long, thin legs.
Do Fungus Gnats Harm Chilli Plants?
Adult fungus gnats feed on the decaying organic material found in houseplant compost and will not really cause any direct damage to your plants.
The biggest problem with fungus gnats is associated with their eggs and larvae: fungus gnats lay their eggs in the compost and, once hatched, the resulting white coloured, black headed, larvae will feed directly on the roots of your plant. This can cause significant damage to seedlings and weaker plants, resulting in wilting of the plant and affecting growth.
With this in mind, as soon as I realised that I had a problem with fungus gnats my top priority was to get rid of them!
How can I get rid of Fungus Gnats From my Chilli Plant?
Adult fungus gnats typically live for around 5 days and will lay eggs in the compost of the plant.
Here we will take a look at the 3 main methods that I used to try and eradicate my fungus gnat infestation. These methods in combination target both the adult gnats as well as their eggs and larvae.
1 – Don’t over water
Fungus gnats love damp, moist compost so the most important thing to do to stop an infestation is to make sure that you don’t over water your plant.
I now water my chilli plant about once every two days.
By following a cycle that gives the compost the chance to dry out slightly between watering, the roots of the chilli plant are forced to search for the moisture that the plant needs, making them stronger. This should help produce a strong and healthy plant.
Tell tale signs that you are not watering your plant enough will be the wilting of the leaves. If you see this, you probably need to water more!
An overall drier compost will help discourage gnats from laying eggs.
2 – Use Fly strips
I bought some yellow fly strips cheaply off Amazon for just a few pounds, after hanging a couple of the strips close to the compost of my chilli plant for a few days, I caught plenty of adult fungus gnats.
Fly strips are available on Amazon below:
Every one of the adult flies that I caught were potential parents to new gnats so the strips are a good way of reducing the numbers of both present and future gnats.
If you don’t want fly strips hanging around the house a good alternative is to use decorative sticky traps. These traps can be placed in the compost near to the base of your plant, check them out on Amazon here:
3 – Cover the compost with gravel or sand
The surface of the compost is the breeding ground for fungus gnats – by removing the very top layer of compost and replacing it with a covering of either sand or gravel you can further help stop fungus gnats from being able to feed and lay eggs.
By restricting access to their breeding ground this should massively impact their ability to reproduce.
If All Else Fails… Repot Your Chilli Plant With new Compost
If you are still having limited success, a more extreme measure is to repot and replace the compost of your chilli plant.
When choosing a compost to use indoors it is best to opt for shop bought compost over compost you have made yourself. Shop bought compost is much less likely to be harbouring potential pests as it has usually undergone a process of sterilisation.
When repotting, be sure to wash and clean the pot before refilling it with new compost.
