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1. Cannabis Caterpillars and Inchworms

How to identify caterpillars and inchworms on cannabis plant

Cannabis caterpillars and inchworms are something that every producer must control and identify. Expert and rookie cannabis farmers understand that pests can ruin a plant, no matter how carefully it is watered, nourished, or tended to.

One of the strategies to assuring that your plants grow into healthy, robust, and consumable cannabis is to keep a watch out for any pests that may infiltrate your growth and then take the necessary steps to exterminate them without destroying your garden. Not only will it keep the plants alive, but healthy plants have more energy to create trichomes and terpenes, resulting in increased bud production.

Sometimes the first evidence of caterpillars and inchworms is just missing leaves. Caterpillar feces may also appear as clusters of black/brown “dirt” on your leaves. Finally, you might notice a caterpillar nibbling on your leaves.

What causes caterpillars and inchworms on cannabis?

Caterpillars and inchworms are a big cause of worry for cannabis growers. Numerous caterpillars and inchworms might harm our plants, as well as various treatments. The most important thing to do to keep any of these pests from wreaking havoc on your plants is to prevent them from becoming infected in the first place. If you cannot avoid the attack of any insects or mites, you must identify which are causing the problem to regulate and eliminate it.

How to get rid of caterpillars and inchworms on cannabis?

Below are hints to help you in solving typical garden riddles, as well as pest-control (caterpillars and inchworms) advice:

Oils for Horticulture

To keep bugs from consuming them, many plants have evolved their defenses. Horticultural oils tap into the power of your plants by refining and using their oils to control pests. In reality, many natural insecticides are based on the oils of various plants. Horticultural oils also don’t leave a film on your plants, which is a plus. However, because they don’t stay very long (about 8 hours), you’ll want to apply them every day or combine them with other solutions. These therapies will necessitate the use of a mister. Pesticides that contain horticultural oils include Lost Coast Plant Therapy, Essentria IC3, and Peppermint Oil.

Effective towards: Aphids, barnacles, broad mites & russet mites, caterpillars, cabbage loopers & inchworms, crickets, fungus gnats, mealybugs, scales, spider mites, whiteflies.


Spinosad solutions are entirely safe for pets, children, and plants. You can apply spinosad products directly to kill bugs on contact, and they should be sprinkled abundantly anywhere you detect bugs, particularly underneath the leaves. Although it may not be as effective against pests as some of the more potent insecticides, it accomplishes the job and is completely safe for plants, animals, and humans! Spinosad is an excellent choice for organic and outdoor producers because it is harmful to numerous pests but less toxic to many helpful insects and spiders. Usually, spinosad treatments are only effective for around 24 hours after mixing with water.

Effective towards: Aphids, cabbage loopers & inchworms, grasshoppers, whiteflies, crickets, leafhoppers, leaf miners, spider mites, thrips, and caterpillars.

Caterpillar BT Spray (harmless biological insecticide)

In this biological insecticide, the Bacillus thuringiensis (Bt) kills larvae and inhibits caterpillars from eating. Ensure to obtain anything designated for caterpillars, as there is another sort of BT that is excellent on mosquitos but not so well on caterpillars. It isn’t efficient against all bugs, but it is one of the most valuable methods of killing caterpillars and won’t harm most useful insects. It can also kill other cannabis pests such as worms and moths as an added advantage.

Effective towards: Caterpillars, cabbage loopers & inchworms, leaf miners (some species), and moths.

Neem Oil

Neem oil is non-toxic, organic, and efficient against a wide range of pests, molds, and fungi. This product can be used in terms of safety until the day before harvest. However, as with any pesticide, avoid getting any on your buds because it may end up influencing their ultimate taste and fragrance if it doesn’t have enough time to evaporate before harvest. Neem oil is a natural medicine that is particularly effective against various nasty bugs and mold but will not harm humans, animals, or most “good” bugs such as bees, ladybugs, predatory wasps, etc.

Caterpillars on cannabis
Neem oil is a great way to stop black caterpillars on cannabis.

It’s easy to see why Neem oil is one of the most extensively used and efficient pesticides in the grow room. When we polled our readers, we discovered that gardeners use it eight times more than the next most popular pesticide, natural or not. Some people have experienced adverse reactions to buds cultivated with Neem Oil as well as Neem Oil itself. Furthermore, some people are allergic to Neem Oil, which might cause serious problems when they smoke buds grown with Neem.

Effective on: Aphids, barnacles, broad mites & russet mites, caterpillars, cabbage loopers & inchworms, crickets, fungus gnats, fungus and mold, grasshoppers, leafhoppers, leaf miners, mealybugs, scales, spider mites, thrips, and whiteflies.

Dealing with caterpillars and inchworms outdoors 

Growing cannabis outdoors may be an advantageous experience, but it is not without its own set of obstacles, and caterpillars and inchworms can be a major stumbling block. Neem oil, beneficial insects, companion planting, and netting are just a few of the methods you can use to prevent pests from your cannabis farm. Caterpillars are the most prevalent cannabis pests encountered when growing cannabis outdoors. If you have any plants outside, conduct a brief check to see what bugs you can discover as a test. Even the most well-kept gardens and lawns will produce something.

Stop caterpillars and inchworms before they become a problem

Cultivators often encounter caterpillars and inchworms through no fault of their own. Even if you take every care, caterpillars and inchworms may still infest your grow space. No amount of attention will prevent pests from entering grow rooms; their lives are dependent on devouring your plants! However, you can avoid most insect (caterpillars and inchworms) infestations with a bit of forethought.

  • Become familiar with cannabis pests and diseases so you can identify them.
  • Commit to cannabis cultivation best practices.
  • Take measurements and make adjustments to your cannabis plants’ habitat.
  • Take a multifaceted strategy to pest control.
  • Use insecticides on your cannabis crop regularly.
Picture of Ed Rushford

Ed Rushford

Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. 𝕏

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