Caterpillars - a late-summer pest in your Cannabis Garden

The photo above: You might not see the caterpillar because it is already burrowed deep into the flower, but you can spot its feces. If you have caterpillars botrytis is not far behind. It grows on the feces and the areas where the caterpillar damaged the plant. It pays to be vigilant! Photo by Christian Petke

In July, my newsletters discussed battling plant enemies like bugs and mold. But there’s another cannabis enemy that may affect your garden later in the season: caterpillars.

Caterpillars are the larval stage of butterflies and moths. Caterpillars are often the same color as leaves, so they are hard to spot. There are a range of caterpillars that commonly infest cannabis. This includes corn earworms, cutworms, cabbage worms, and corn borers.

Caterpillars are voracious eating machines and can savage plants very quickly. They chew continuously to support their high growth rate. They can destroy a tray of seedlings overnight. 

Photo above; Something will always nibble on your plants but make sure the critters don't take over your grow. Photo by Christian Petke

Leaf-eaters leave large holes as calling cards in the leaves they dine on. Corn earworms, cabbage worms, and other caterpillars also infest buds. A bud that turns brown and wilts “for no reason” may house a caterpillar consuming it from within.

Caterpillars reproduce slowly compared with many pests, but they have large appetites and each one can cause a lot of damage.

The best way to get rid of caterpillars is by using Bacillus thuringiensis (Bt), which is a bacteria that causes plague in caterpillars and is not interested in humans or pets. Bt is applied as a spray or more effectively using a fogger. There are many brands on the market, but the main ingredient should be Bacillus thuringiensis (Bt).

Another method of controlling caterpillars is to introduce predators. Options include spined soldier bugs, minute pirate bugs (Orius insidiosus), and green lacewings. Parasitic nematodes (S. feltiae) control subterranean larvae.

BT and an industrial strength Fogger. Here is one with great ratings and a great discount. Photo by Christian Petke