Mourning or do you have black flies at home?

Small but very annoying black flies flying out of flowerpots are among the most common pests of indoor plants and the most frequent disturbers of peace in the home. If action is not taken in time, soon there are so many of them that they fly around, sit and annoy absolutely EVERYWHERE. Do you know how to get rid of them effectively and as quickly as possible?


In this article, we will introduce you to proven and generally recommended methods that can make the fight against blue eyes easier for you, as well as tips on how to prevent blue eyes!

Sorrel - what are they and how do they harm us and plants?

Mourning flies are small, black-gray flies that most often fly near plants or sit on the substrate, so you may not notice them right away.

Adult midges are approximately 2-4mm, and one adult female midge can lay up to 200 eggs in the substrate for your plants. Adults don't actually harm anything else - but for many of us, they "drink blood" just by being in our household.

White larvae , which are almost imperceptible to the eye (they are about 1 mm) hatch from the eggs due to moisture (most often from watering ). It is these larvae that can cause a big problem for plants when they multiply, because in addition to dead organic matter, they also feed on roots and tissues, especially of young plants. They can also transmit various plant diseases (molds and fungi).

You can usually identify a plant that is infested with mealybug larvae by its drying and wilting.

The life cycle of ladybugs (egg – larva – adult) lasts approximately 3 weeks. If you have more favorable conditions at home (warmth, humidity), the cycle can be accelerated to 1-2 weeks.

For this reason, it is necessary to act immediately when the first flying invaders appear!



Prevention - watch out for new substrates and new members of the jungle!

Mourning bags most often get to your home in one of two ways. Firstly: their eggs are found in the purchased substrate (unfortunately, this happens often) or secondly: you bring them in the substrate together with a new plant from the store, from friends - they simply sneak to you hidden in the dirt.

You can prevent their "awakening" in several ways.

Sterilization of the substrate : the easiest way to make sure that you don't hatch bugs in the newly purchased clay is to clean it before using it.

We can let the substrate dry for 1-3 days before use, but it is more effective (and safer) to burn the clay in an oven or microwave (we lay out the substrate on a baking sheet and let it burn in the oven - but be prepared for the fact that this process can be accompanied by an unpleasant smell). Remember that if you are going to overfire the clay, it needs to be wetted after it cools so that it can later absorb the water from the potting mix.

Flushing: The substrate can also be rid of intruders by pouring it with a solution of potassium permanganate or a solution of hydrogen peroxide.

You can be inspired by grandma's advice and stick cloves of garlic into the clay; use broth from nettles and onions as the first dressing; smokers can use tobacco infusion (butts and tobacco left to soak in water for half a day) and if you search, you will surely come across many more…

Test for the presence of larvae: do you want to be sure that you have not brought an intruder into the substrate? Cut a raw potato and place it cut side down on the ground. Check it after 48 hours. If there are caterpillar larvae in the substrate, you will find them on the potatoes.

Special fertilisers: You can also prevent the fight against blackheads with special types of fertilizers (e.g. from the brands Floria, Vitality complex, Substral Careo). They are available either in liquid, granular or stick form .


A couple of black flies - a quick fix!

As soon as you notice the first black fly, it is in your best interest to act before the damselflies have had time to reproduce properly.

Drying out of the substrate: you can get rid of weeds simply by stopping watering the plants for a while and letting the root ball dry out. In dry conditions, very often these annoying flies do not survive, and above all they cannot reproduce.

If you have plants that could be harmed by the drying out of the substrate, try a combination to kill the adults (glue tapes/boards, see below) and get parasitic nematodes (see below).

Sprinkling the substrate: if any of the larvae survive the drought, you can prevent them from hatching by covering the top of the substrate with sand or small stones, which will ensure that the young fly cannot fly out. Surviving larvae can also suffocate in this way.

Destruction of adults - flies: the most effective way to get rid of flies is to place adhesive tapes or boards near the plants (the most commonly sold ones are yellow, you can also find blue in our e-shop ), which will attract the adults. The fly sticks to the tapes and thus does not lay any more eggs.

Outnumbered, now what?

Sometimes, however, it can happen that sad women are faster and manage to hide from us until they simply multiply. Don't worry, you can still get rid of them, and quite quickly.

It is important to continuously catch the adults, so you will definitely need yellow adhesive tapes. Every additional weevil attached means fewer eggs and potential larvae - and that counts!

Removal of the top substrate: you can also kill the weevils by thwarting their reproduction efforts by removing and disposing of the top part of the substrate. Simply remove the top 1-2 cm of soil from the plants (this is where the fertilized eggs are located) and then sprinkle with new soil.

Parasitic nematodes (genus Steinernema feltiae ): the gentlest and most effective way to get rid of overpopulated worms is to use their natural enemies – parasitic nematodes. When using them, follow the instructions included in the package. These beetles are applied by watering the soil, in which they search with their sense of smell and then eliminate the larvae of the weevils.

Nematodes are completely harmless to humans and plants. You don't even have to worry that there will be bugs everywhere instead of flies - as soon as the nematodes destroy the larvae of the ladybugs, they will disappear on their own. So if there are no ladybugs, there won't be nematodes either.

When buying parasitic nematodes, be careful that you buy the right ones against blackworms (there are several species that specialize in specific pests).


Fighting annoying insects can sometimes be a difficult and lengthy process, but never give up - our plant jungle is worth it!

Jana Beránková

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