Aug 25, 20212 min read

KNOW YOUR ENEMY: Caterpillars

A weekly lesson in pest management for indoor gardeners. This week we will talk about how to combat caterpillars on outdoor grows.

What caterpillars cause problems

Before you head outdoors and begin smashing every wiggly worm in sight, please note that not all caterpillars are out to hurt your cannabis. There are a number of them that can do real damage though, so learn more about these particular pests to protect your plants.

The most common harmful caterpillars include

Cutworms
Cabbage Worms
Leaf eaters
Corn borers

What do the caterpillars want with our cannabis?

Ever read the hungry caterpillar when you were a kid? Then you know what they want - food! These creatures have to eat a massive amount of green before they can think about metamorphosing into their butterfly or moth state. Due to the energy requirements, caterpillars will go nuts on your plants and eat them all up. Some enjoy munching on the leaves, other prefer stems, and even the buds!

The only thing worse then having a caterpillar eat through your plants is having them lay eggs on it to create new caterpillars to eat through all of your other plants. Caterpillars typically lay their eggs in the shade on the underside of leaves, and will take time to do so in between cannabis plant feasts.

Signs of caterpillar damage on a cannabis plant

There are a few things you will notice right away, even if the caterpillars are hard to find.

Large holes in leaves.
Leaves missing the green plant matter and appear see-thru with just veins remaining.
Large quantities of leaves are missing.
Stems look weak, signs of something boring through your stem.

How to defend your cannabis from caterpillars

Short term solution

Pull them off and squish! The immediate solution is to throw on some gloves and start picking them off. If your plants are sturdy enough, you can give them a solid shake by grabbing the stem a little below center of the plant and moving them around a bit. Using a spray feature with your hose can also help to knock off pests from your plants, but is not recommended if it will overwater your plants.

While you consider your long term management plan, you can throw some protective netting over your plants for the short term and work to manually keep your plants clean.

Long term solution

Assume there will be caterpillars for grows to come, and develop a plan to combat the caterpillars over the course of your season.

Using a regular spray in seasons caterpillars are common will help prevent and combat dangerous build ups of the pests. Many growers use BT, or Bacillus thuringiensis which is a bacteria harmless to humans and pets, but deadly to the caterpillars. Neem oil sprays on plants that are not flowering or cinnamon teas brewed at home are other organic options you can use on your plants as caterpillar season approaches or directly after noticing the insects on your plants.