Just like any plant, cannabis can suffer damage from insects. A couple of bugs and pests can totally mess up your marijuana harvest. Now this is a major problem that’s on the rise since you have to consider the cost in growing and maintaining your cannabis plants. Typically, these bugs end up destroying the leaves and the buds of marijuana before they even mature, giving you low quality weed that’s not even going to get you high when you smoke it.

Here is some of the most common weed pest and bugs that you might need to deal with if you’re growing marijuana.

Fungus Gnats

While the adults don’t bother the cannabis plants, these weed pests bring harm to your plants during their larvae stage. The fungus gnat larvae actually burrow into the ground and eat at the roots of the cannabis plants. This prevents the plants from absorbing the nutrients and water that they need for their growth.

Fungus Gnats
Fungus gnats pest

There are several reasons that fungus gnats can be attracted to your cannabis plants which include over watering your cannabis plants, having wet topsoil or a lack of air circulation. One of the easiest solutions to remove fungus gnats is to water your plants properly.


These are soft round or oval-shaped insects that may come as green, yellow, brown, or light greenish in color. Aphids use their mouths to suck on the sap of the cannabis plants and they lay their eggs under the stems of the plant. Infestation of aphids in cannabis can lead to a lot of problems which include inadequate growth, damaged leaves and stems, and cause sooty mold because of the substance called “honeydew” that the aphids produce.

Early detection of aphids is a preventive measure to ensure that you cannabis plants don’t have aphid infestation and specialized insecticides are effective measures to remove these weed pests from your cannabis plants.

White Flies

Belonging to the all too common weed pests, white flies can hide under the leaves of the plant and suck at the nutrients of the plant. This can result in white spots on the leaves which can lead to inadequate nutrition for the plants and poor growth of the cannabis.

Fortunately, it’s quite easy to detect the white flies on the plants and an effective way to remove them is by using the pesticide SM90 mixed with water with a 1:5 ratio respectively. But be sure to do this during dark if you don’t want the leaves to get burned.

Slugs & Snails

These weed pests can cause slight to irreparable damage to your cannabis. While there is no foolproof way to eradicate slugs and snails, you can use physical barriers to block their path and protect your plants. Set up a wall and sprinkle lime juice, eggshells or sawdust around your plants. You can also encourage toads, frogs, and beetles to grow in your garden since they eat snails and slugs. Note that these slugs and snails often attack at night and early detection of these annoying pests is important for the growth of your plants.

A slug, pest to Cannabis