Mealybug, accompanied by ants for its honeydew.
Mealybug on a leaf.
Breeding of mealybugs by ants.
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Mealybugs, predators of your plants
Contents
Find all our tips in the application
The mealybug, whose scientific name is Pseudococcus viburni, is a parasitic insect of the Pseudococcidae family (order Hemiptera). It measures between one and five millimeters. Its oval, segmented body is covered with a white, cottony, powdery wax. This secretion protects and conceals the eggs (ovisac).
Only females, larvae or eggs are found on plants. At the end of the larval cycle, the male becomes a flying insect. The female has no wings. She lives attached to the plant where she lays her eggs.
The color, shape and appearance of mealybugs vary according to species (there are over 7,000). Some have a soft body enveloped in waxy filaments, while others have a hard body covered in wax, or a soft body protected by a wax shield.
Within this numerous family, two species stand out, as they attack all indoor plants and outdoor indoor plants:
Within this numerous family, two species stand out, as they attack all indoor plants and outdoor indoor plants:
- orange mealybug(Planococcus citri) ;
- greenhouse mealybug(Pseudococcus longispinus).
Contributing factors
Mealybugs thrive in warm, humid, confined environments. High humidity and temperatures above 27°C increase the number of eggs laid per clutch. Tropical environments, heated greenhouses and cold-sheltered nurseries encourage their development.
Certain urban pollutants are also thought to have an effect on their proliferation.
Certain urban pollutants are also thought to have an effect on their proliferation.
How it works
The cochineal is a sucking and biting insect. It pierces the stems and leaves of plants with its rostrum to feed on their sap. If left untreated, the invasion leads to total dieback.
Mealybugs produce a sticky, sweet substance called honeydew, which prevents photosynthesis. This secretion encourages the appearance of micro-organisms known as fumaginia. They give a blackish appearance to the surface of the diseased section.
During cold spells, this pest overwinters, sheltering in plant cavities or at the crown. In spring, it returns to the aerial parts of the plant.
Crops contaminate each other when they are close together or during maintenance. Undisinfected tools, hands and clothing are all vectors of contagion. However, the origin of the infestation is very often linked to the purchase of an already colonized plant that is brought into the home.
Symptoms
The scale insect is small and inconspicuous, but certain stigmas give it away. The plant is weakened, its leaves deformed and prematurely yellowed. On the underside of the leaf blades and on the stem, there are cottony clusters, black spots due to fumagine and sticky droplets that attract ants.
On closer inspection, brown hulls and insects can be seen at leaf or vein intersections.
Treatment
As soon as the diagnosis is made, isolate the plant if possible. Preventively spray other plants with nettle or fern slurry.
Depending on the degree of infestation, there are several natural solutions available to eradicate mealybugs.
Mealybugs hate water. You can therefore spray the plant with a fairly powerful jet. Remember to cover the pot with a plastic bag to prevent the pests from taking refuge there. Repeat the operation until the pest has completely disappeared.
You can also prepare an ecological spray solution. Mix one liter of water with
- one teaspoon of methylated spirits ;
- one teaspoon of olive oil (or vegetable oil);
- one teaspoon of black soap.
This solution should be sprayed twice in succession, then once a week until all larvae and eggs have been destroyed.
A spray treatment based on an infusion of garlic heads can also be tried.
Soil can be infested. For potted plants, get rid of the substrate and disinfect the container. Don't throw anything into the compost, as this could contaminate future plantings.
If the plant is severely infected, cut it down, change the pot and quarantine it for at least 6 months.
For biological control enthusiasts, why not introduce the mealybug's natural predators , ladybugs or bugs? They devour all species, at all stages of development.
Replanting host plants (nettles) or melliferous plants, sowing meadows, are all ways of attracting auxiliary insects. What's more, they contribute to the garden's biodiversity.
