Parassiti, come riconoscerli e combatterli, consigli e interventi. Parte generale. -

Parasites, how to recognize them, treatment, prevention and intervention.

Parasites are not always easy to discover, but the damage they cause to the plant is. The caterpillar, the white fly and the miner fly, and many others, attack the plants and seriously damage the crop. If action is taken quickly, these harmful insects can be eradicated.

Let's see how to behave in these cases.

Even less experienced growers have knowledge or experience of the most common parasitic insects that attack cannabis plants: lice, caterpillars or whiteflies.

Prevention is naturally the first path that everyone must take, paying close attention to obvious manifestations and knowing the "disinfestation" methods.

With our indications you will be able to recognize and act in real time.

The Mining Fly:

This parasite attacks cannabis plants differently depending on the type. It deposits its eggs inside the leaves and after a couple of weeks they hatch. The larvae begin to dig tunnels, a clear sign of their presence.


An obvious sign of the presence of miner flies are dark traces along the leaves, brown lines. These are the tunnels that the larvae are digging inside the leaf, eating the inside. Furthermore, it is possible to notice small holes that are caused by the adult flies.


Usually this parasite is typical of outdoor crops.

The first method is the physical one: eradicate the larva that is in the tunnel with a small knife or using your nails, we will find it along the tunnel.

You can also use Neem Oil in combination with sticky traps.

The little red spider:

Common parasite The red spider is voracious and very dangerous, even if very small it is visible due to its bright red colour. He manages to cause damage in a short time and if in a group he is capable of taking out a plantation in a single night.


The leaves of the plants will begin to show white or in some cases even black or yellow spots above and below the leaves. Unfortunately, the symptoms can be interpreted by the grower as deficiencies. In these cases, to remove any doubt, it is better to use a magnifying glass to find the intruder who appears red-orange and sometimes brown. Like all spiders they can leave a web.


Keeping the cultivation space clean is essential to avoid the arrival of the red spider, which is at ease in conditions of stale and dry air. The temperature must not rise above 27° and the humidity 50/60%. The affected part of the plant can be washed with water, minimum 40%, and nebulized alcohol.

Neem oil is always a great product as is potassium soap.

The Caterpillars:

Voracious and difficult to identify, caterpillars can devour your plantation extremely quickly, it is important to intervene as soon as possible to avoid serious consequences.


The first sign you will be able to spot is the presence of small translucent yellowish ovules on the leaves, as well as tiny black traces which are the feces of the caterpillars themselves. If the caterpillar has already established itself for a while you will also find actual bites on the leaves of the plants, as well as rot in the shoots and even more mold.


The first method of intervention is certainly the manual one, remove the caterpillars from the plant, this operation is not simple because they camouflage themselves very well being green in colour.

Another classic method, to be used anyway, is to make a mixture of garlic and chilli pepper by spraying it on the plants.

Insertion of antagonistic insects, in this specific case a type of Wasp.

The Trips:

Complicated to manage especially with plants made from cuttings. It is a very small and rapid parasite which is why it is even more important to act immediately to avoid damage. Neem oil can prevent its arrival, but if it is already present, act immediately.


When the plant is attacked by Trips it is possible to see silver-colored marks on the leaves and in some cases small dots (feces), broken leaves due to the fact that the Trips suck the sap and therefore cause the plant to wrinkle and break. Placing adhesive traps will help you identify the presence of Trips.


As in many other cases, neem oil sprayed on the plant is always an excellent method as is potassium soap, but in the final phase of flowering it would be more appropriate to insert antagonistic insects such as wasps. Another possibility is the introduction of a mushroom "verticillum Lecanii" which is excellent for combating trips.

The White Fly:

A common parasite, the Whitefly is essentially a sucker. It does not cause serious damage to the plant but makes it weak.


The Whitefly is easily visible, buzzing near your plants. You will also notice yellowing of the leaves and a myelous substance, secretion from the flies themselves. In some cases even white powder on the leaves.


One of the methods used is to plant plants nearby (not in the same pot) that ward off this type of parasite, such as basil, as well as the introduction of predatory whitefly insects in this case too.

Chromotropic traps are also a good way to get rid of these insects, using neem oil and potassium soap to be administered about once a week until the problem is resolved.

Lice or Aphids:

The louse is another parasite that is "fast" in infesting and reproducing. When dealing with this insect it is necessary to be very quick in action.


The leaves of the plants begin to turn yellow and dry out. You will find on the underside of the leaves and also along the stems a honey-like substance (molasses) produced by the louse. This parasite is a symbiont of the ant, which is why their presence could be a warning sign.


When working indoors, obsessive hygiene is necessary, changing before entering the cultivation room is very important so as not to cause lice to proliferate outside too.

Physical elimination is simple because they don't move much. As always, the insertion of antagonistic insects such as larvae of lacewings is one of the most useful and totally organic methods. Outdoors you can try with ladybugs which are predatory insects, as well as some mushrooms.

The louse often occurs when excessive fertilizers are used and proliferates in dry environments. Another tip is to always remove all decaying fallen leaves.

The Cochineal:

Cochineal is one of the most well-known parasites of all, and attacks an extremely large number of types of plants. Cochineal infestation naturally occurs outdoors but also quite frequently indoors. They are microscopic parasites and very resistant to many insecticides. They can reach the root system of the plant further worsening the situation and their feces contain a devastating fungus commonly called "sooty mold".


The cochineal is brown or white in color with a sort of whitish fuzz. They will initially be seen on the stems and will then spread throughout the plant. Rose plants, olive trees and cacti can be a big problem if they are close to our plants. Also in this case the presence of ants can be an indication of cochineal infestation.


Pass a mixture of water and alcohol with cotton wool over the plant. On the parts that are very affected and therefore in serious conditions it is necessary to prune.

The substrate midge:

Also known as the soil midge or black midge, it measures 4.5 millimeters and undergoes several transformations from larva (underground) to flying midge.


Particularly at ease in humid environments, it can be found at the base of plants, look for them in this area, as they are winged insects, they will fly around the plant.


Use neem flour or predatory insects to place in the substrate such as Hypoaspis geolalepumites.


Nematodes, or round worms, are not necessarily harmful to cannabis plants, but among the many species some can also cause death.


The plant begins to slow down its growth, yellowing and general discoloration of the leaves, weakness of the plant which is in lack of fluids and can rot.


Try to change the entire substrate trying not to damage the roots and use a new one. Use neem oil. Using Trichoderma mushroom is an excellent method to fight nematodes and make an important contribution to the plant, this mushroom in fact goes into symbiosis with the root system of cannabis and reactivates the substrate.

Snails and Slugs:

These insects are very well known, they range in size from 1 to 9 millimeters and have a slimy and mushy body. Snails, as you surely know, are accompanied by their hard shell. The slowness of these little animals is well known, as is the trail of mucus they leave as they pass. It is rarely found in indoor cultivations, but when its presence is recognized outdoors, an intervention is necessary since they are greedy for cannabis.


The classic shiny slimy trail left in their passage

Bitten leaves.


Surround the plants with a strip of salt.

Put bait like jam that attracts them.

You can use antagonistic insects such as Rumina.

Of course you can physically eliminate them, it's a simple job. I always recommend the night hours because they are more active, use a torch possibly with green light to locate them.

For all the topics we have talked about and for others, we invite you to learn more in the sections dedicated to the individual problems.


AfidiAntiparassitariBruchiCoccinigliaColtivazioneInfestazioneInfestazioniInsettiLavaggioLimacceLumacheMosca biancaMosca minatriceMoscerinoMoscerino del substratoNematodiOlio di neemParassitiPrevenzioneRagno rossoSalute della piantaTrip