How to Get Rid of Caterpillars on Cannabis

How to Get Rid of Caterpillars on Cannabis

Both amateur and professional cannabis growers share a universal dread: menacing caterpillars. As unassuming as these creatures might look, they can cause extensive damage to your cannabis plants, making them a pest that growers must learn to effectively control. In this guide, we will delve into identifying caterpillar infestations, the harm they cause, and tried-and-true methods for getting rid of them.

Unmasking the Enemy: Caterpillars and Cannabis

Caterpillars, the larvae of moths and butterflies, are habitual munchers that feast on the leaves, stems, and buds of your cannabis plants. On a mission to consume as much as possible before their metamorphosis into moths or butterflies, they can cause massive damage in a relatively short period.

Identifying Caterpillar Infestation

Caterpillars themselves often have superior camouflage, blending in perfectly with the color of the plant foliage. However, they leave behind tell-tale signs of their presence:

Physical Evidence

Look for irregular, jagged holes in your foliage. Bite marks may also appear on buds or stems.

Frass Presence

Frass, or caterpillar droppings, are a clear sign. They often appear as small, blackish pellets surrounding the base of your plants and on leaves.

While some caterpillar damage may superficially resemble that from other insects, their large size and the presence of frass usually confirm it’s the work of caterpillars.

Caterpillars on Cannabis: The Damage They Cause

While munching leaves make your cannabis plants less aesthetically pleasing, the real danger with caterpillars is their potential to harm your yield directly. They often bore into the heart of your precious cannabis buds, feasting from the inside out. They leave behind waste and partially eaten plant matter, which can foster mold and bacteria growth, damaging your crops.

The infested buds are not only unsightly, with significant portions eaten away and discoloration from waste and mold, but they can also pose health risks. Consuming or smoking mold-infected cannabis can lead to serious lung infections, especially in individuals with compromised immune systems. This significant possibility makes an infestation a severe threat to the safety and quality of your cannabis crop.

Battling Caterpillars: Preventive and Reactive Measures

Prevention is the first and foremost line of defense against caterpillars. Erecting barriers before these pests assault your cannabis plants can save significant time, money, and stress. However, if caterpillars manage to breach your defenses, several curative treatments can effectively annihilate them and save your crop from total devastation.

Preventive Measures

Efficient prevention can keep caterpillars from reaching your cannabis in the first place. Here are some strategies you can employ:

Crop Rotation

Changing the type of plants seasonally can confuse and deter egg-laying moths. Moreover, growing different plants can improve your soil’s fertility over time.

Companion Planting

Integrating plants that attract natural caterpillar predators can significantly reduce their population. Plants like marigolds and cosmos attract insects like lacewings and parasitic wasps that are known caterpillar predators.

Physical Barriers

Employing fine mesh netting over your plants can prevent moths and butterflies from laying eggs on the foliage or buds.

Reactive Measures

If the preventive measures fail, don’t despair. There are several reliable methods to rid your plants of caterpillars:

Manual Removal

This method is labor-intensive but can be very effective for smaller gardens. Regularly inspect your plants for signs of caterpillars or eggs. If found, remove them and dispose of them far from your plants.

Biological Controls

Bacillus thuringiensis (BT) is a beneficial bacteria that specifically targets the digestive system of caterpillars. Once consumed, it causes them to stop eating and eventually die. BT does not harm other beneficial insects and is generally safe for humans and pets. Spray it on the leaves and buds of your plants.

Use Natural Predators

Releasing natural predators of the caterpillar, like Praying Mantis, Ladybugs, and beneficial nematodes, can be an effective and eco-friendly way to keep their numbers in check.

Insecticide Application

In severe infestations, you may have to use targeted, caterpillar-specific insecticides. Always be sure to use products that are safe for cannabis and won’t contaminate your buds.


Unarguably, caterpillars pose a significant challenge to cannabis growers. If left unchecked, they can decimate your crop, leaving you with unsightly and potentially hazardous cannabis buds. However, by implementing vigilance and targeted control strategies, growers can win against these munching pests. Prevention through crop rotation and companion planting can go a long way in keeping caterpillars at bay. If an infestation does occur, it’s important to act swiftly with manual removal, biological controls, natural predators, or safe insecticides to stop their destructive march on your plants. Remember, in this battle, a stitch in time not only saves nine but ensures a healthy, bountiful cannabis harvest.

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