Caterpillars & Inchworms

Stop Caterpillars From Attacking Your Cannabis!

Caterpillars!!! Argh!!! Sometimes the first signof caterpillars / worms / cabbage loopersis just seeing chunks of your leaves missing. You mayalso see clumps of black/brown dirt on your leaves, which is caterpillar poop. Lastly, you may actually catch a caterpillar munching on your leaves. It can be so angering to catch them in the act!

Zebra caterpillar on a cannabis leaf, picture by Whitney Cranshaw of Colorado State University

Saltmarsh caterpillar on cannabis leaf, picture by Whitney Cranshaw of Colorado State University

Saltmarsh caterpillar on cannabis leaf

Another saltmarsh caterpillar on a marijuana leaf, picture by Whitney Cranshaw of Colorado State University(thank you!!!)

Saltmarsh caterpillar on a marijuana leaf

You’ll see chunks of your leaves missing from the caterpillars devouring your leaves

Caterpillar damage on cannabis leaves
caterpillar leaf damage pic by molpes

Caterpillar damage on a marijuana leaf - this is the back of the leaf

Caterpillar Droppings on Leaves

Caterpillar poop on a cannabis leaf

You Actually See Caterpillars, Inchworms or Cabbage Loopers

Example of an inch worm / caterpillar on a cannabis leaf. You can even see a hole in the leaf where it was eating! Grrrrrr
Cabbage looper crawling on a marijuana leaf
A closeup of a caterpillar
Caterpillars can be a cannabis grower's worst enemy!
A small green caterpillar on someone's finger for scale
A little green caterpillar chomping down on some cannabis leaves

Proven Caterpillar Remedies

  • Caterpillar BTSpray(safe biological insecticide)“ Thisbiological insecticide contains thebacillus thuringiensis (BT) bacteria which kills larva and prevents caterpillars from being able to eat. This is one of the most effective ways to kill caterpillars, and won’t hurt most beneficial insects. As a bonus, it also killsother cannabis pests like fungus gnats, worms and moths. Apply a caterpillar BT sprayas soon as you see leaf damage, caterpillars or caterpillar poop. BT spraysworkbest on small caterpillars that are actively eating your leaves.Repeat everyweek for as long as you’re still seeing caterpillars, though you can give BT more often if there’s a heavy infestation. Make sure to thoroughly mist both the tops and bottoms of leaves, and apply again after a heavy rain (since that will wash the BT away). Since BT is harmless to humans, you can use BT products up to the day of harvest! One thing to keep in mind is BT spray almost instantly stops caterpillars from being able to eat, but doesn’t kill them directly. So although you may see the caterpillars alive and apparently unharmed after spraying, the BT is still doing its dirty work.
  • Spinosad Products(safe & organic)“ Although not as effective against caterpillars as a BT product, Spinosad can be a good choice, especially if your plants arealso suffering from other insects like aphids, spider mites, thrips or white flies since this will attack all of them at once.Spinosad products are organic andcompletely harmless to pets, children, and plants. Unlike many insecticides, you can spray properly diluted spinosad heavily on leaves and roots with basically no negative effects. Spinosad products can be used directly to kill caterpillars on contact, but can also be used when watering plants to systematically kill caterpillars via the soil.Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria (actinomycete Saccharopolyspora spinosa) and kills caterpillars via ingestion or contact by effecting the insect nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to caterpillars, but is less toxic to many beneficial insects.Note: Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. Anything left over will be waste.

Recommeded:Monterey Garden Insect Spray with Spinosad
Spinosad products are organic and kill spider mites, caterpillers and thrips

  • Avoid butterflies and moths! Although these beautiful creatures look great resting on your cannabis plants, they lay eggs that hatch into caterpillars! Don’t let them hang around your garden!
Avoid butterflies and moths! They can lay caterpillar eggs!