Lemongrass is a fairly robust plant that can be easily cultivated if you meet the demands for light and warmth. Black mosquitoes can be hard on the lemongrass.© VRD - Fotolia.com
The black mosquito is not hidden from us. If you look closely when watering, you will see the small insects flying up. Adult animals are harmless. The larvae of the moth, on the other hand, pose a problem. Even a small injury to the stalks is sufficient and the pests can penetrate. The root can also be affected. Therefore, you have to be extra careful when watering. The black gnat prefers to lay its eggs in moist substrate. Therefore, you should always water moderately. It is also a good idea to water container plants from below.
The larvae of the mosquito can generally damage the lemongrass in various ways. The black gnats can cause damage to the leaves and growth damage from infestation of the roots as well as a crippled growth habit.
What do black gnats look like and how do you recognize an infestation?
The black gnat occurs worldwide. Even extreme habitats are not avoided. The insects were found in the Antarctic as well as in high mountain regions above 4,000 meters above sea level. Some species live in caves, yet other gnats in the hot desert sun by digging into the sand. However, the black gnat mainly lives in more economic regions, namely in forests, on pastures or in the home garden, where it hides in the plants and in the foliage. Even in the flowerpot on the window sill, the black gnats are viable. Therefore, you have to check the lemongrass more often, especially during the winter.
The black gnat belongs to the family of two-winged birds and, like around 1,800 other species, belongs to the subordination of the mosquitoes. There are around 600 mosquito species in Europe alone. The term moth can be traced back to the dark body and the dark wings. The mosquitoes are about five millimeters in size and have a slim body. The larvae, which are the real threat to the lemongrass, are light to greyish in color and have a fully developed capsule.
By the way, the sciarid mosquitoes can be easily recognized by their slightly prancing flight. The mosquitoes themselves die after a few days and only have the task of mating and reproducing. The larvae can eat mushrooms, bark or leaves. In turn, their excrements serve as food for microorganisms.
This is how mosquitoes can be fought
The trade offers some pesticides against black gnats. However, deltamethrin, magnesium phosphide or pirimiphos-methyl are environmental toxins that are not approved for use in gardens. Inhaling the substances alone can lead to allergies and irritation of the eyes and mucous membranes. There may even be explosions on contact with water. So these substances are a real danger to children, pets and all living organisms. Therefore, do without the chemical club. Black mosquitoes can also be effectively controlled with natural aids.
❍ Use yellow stickers against black gnats:
In the case of yellow stickers or yellow boards, there are talk of colored boards which are provided with adhesive. These boards can be made of paper or plastic. The trade offers different models. Most of the adhesives used are made of polymers. Some products are coated with polyisobutylene. That is why the yellow stickers also appear moist. Yellow tablets with hot melt adhesive appear less sticky. These adhesives are harmless to health and are also used, for example, to attach the labels to apples or oranges. Some boards can also be cleaned with gasoline and used again after use. Here is more about yellow boards.
You can use the yellow boards both indoors and outdoors. Outdoor yellow stickers should be as heat-resistant as possible and should not contain any water-soluble substances. As is well known, insects like colors. They seem to be particularly fond of yellow. But there are also stickers in green and blue available, which have a similar attraction. When approaching the stickers, the black mosquito sticks to the boards. Depending on the plant size, several stickers can be used. You should check the plates weekly and replace them if necessary.
❍ Use home remedies for black gnats:
|quartz sand||If you put quartz sand on the top layer of earth, the soil appears to have dried out and the black gnats are kept from laying eggs on the dry surface. You can use small pebbles as well as bird sand.|
|matches||If you put some matches with the tip down around the plant in the ground, the sulfur-containing components will be released by the water. The larvae die and the black gnats are prevented from laying eggs again.|
|nutmeg||With the active ingredient myristic acid, nutmeg contains an agent which is comparable in its effect to an insecticide.|
|Carnivorous plants||If you place carnivorous plants (e.g. Venus fly trap) near lemongrass, these will help to fight mosquitoes. Carnivorous plants are powerless against the larvae.|
❍ Use nematodes against black gnats in the bucket:
Nematodes are a particularly effective and natural method of fighting the mosquito. These are worms that are not visible to the naked eye and are simply added to the irrigation water. They hit the earth and then attack and kill the moth larvae. For this you need to water several times. It can then take a few weeks for all the larvae to be killed.
Prevent infestation with black mosquitoes - Here's how
Since the black gnat prefers to lay its eggs on a damp surface, you should ensure that the soil can dry well after watering. A layer of sand or pebbles also has this effect. Always remove standing water from plant pots, because lemongrass does not tolerate waterlogging.
When buying plant soil, you should also pay attention to quality. Cheap products are often already infected with black gnats. You should replace infested soil immediately. You can dispose of the soil on the compost, provided that you do not use the compost as a natural fertilizer for houseplants.
By the way:
The method favored by some plant friends of heating the earth infested with black mosquitoes for a certain time in the microwave, with the aim of killing the larvae, seems less promising. Important nutrients are lost to the earth during this process, which ultimately makes them unsuitable as plant soil.