Mealybugs on cannabis plants

Mealybugs can represent a serious pest for marijuana plants. While they rarely attack indoor plants, they are normally found in outdoor crops.

In today's article we are going to see the main characteristics of this sucking insect, as well as what we can do to prevent their appearance or to get rid of them in the most effective way possible.

Mealybugs can cause problems, especially outdoors
Mealybugs can cause problems, especially outdoors

Biology of mealybugs

Mealybugs are insects characterized by having a carapace of different colors and consistencies, depending on the species. This carapace acts as a protective shield against other insects and also against insecticide treatments.

They feed by piercing the plant tissues and sucking sap from leaves, stems, and fruits. They excrete part of this sap as sugary honeydew, which can lead to the growth of a fungus called sooty mold.-

They can breed one or more generations during the year, depending on the species and the climate of the area. They leave the egg as larvae, then they transform into an adult mealybug which lays new eggs that will generate more larvae again. This process (generation) can be performed  1, 2, 3... times a year.

Let's see now how to identify these insects and how to treat an infestation before it compromises the growth of the plants.

Mealybug attached to a branch
Mealybug attached to a branch

 How to detect a mealybug infestation on cannabis plants

In the first phase of the infection, it is an easy-to-eradicate marijuana pest, but the situation can become much more complicated in the second generation since the marijuana buds hide these insects, which are covered by the bud and produce a very unpleasant effect on the final product. We can detect mealybugs in several ways:

  • Identifying the insect, which is usually found attached to the stem. Still, in subsequent generations, we can find them also attached to the leaves
  • Spotting bright and sticky stains on the leaves due to the sugary honeydew (be cautious because aphids and whiteflies also produce these stains)
  • Observing the growth of sooty mold (as before, this fungus can also grow on the honeydew excreted by aphids and whiteflies)

Damages caused by mealybugs

  • Direct damages are caused by absorbing  the sap of the plant, which will gradually lose vegetative vigor.
  • Indirect damages are produced by the sooty mold fungus, which settles on the molasses excreted by the mealybugs. This also debilitates the plant condition, since the leaves of the plants become black (covered by the fungus) and therefore they can't perform the photosynthesis process correctly.

Mealybugs sucking sap from a stem
Mealybugs sucking sap from a stem

How to manage an infestation of mealybugs

These are some of the steps that we should follow to efficiently manage a pest of mealybugs:

  • Remove the most affected parts of the plant
  • Prepare a mixture of water and alcohol at 50% and remove the mealybugs manually with a cotton cloth soaked in this solution
  • Use some organic insecticide like neem oil extract (Neempro by Trabe) or natural pyrethrins
  • We can also use biological control. Both Cryptolaemus montrouzieri and Leptomastix dactylopii are some of the most efficient predators to combat mealybugs.

Specimen of Cryptolaemus montrouzieri, mealybug predator
Specimen of Cryptolaemus montrouzieri, mealybug predator-

So far this introduction to the prevention and control of mealybugs, which as we already know usually appear mainly in outdoor crops. Do not hesitate to leave us your tips or comments when dealing with them, they will surely help all the readers of our Blog.

Happy harvest!


The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.

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