Reply To: What’s best to control caterpillars on marijuana plants?

[E. Vinje]

Hi Russ –

Leaf eating caterpillars can be quite ​a problem in ​outdoor garden​s​ if not taken care of! Caterpillars are the larval stage of the insect order lepidoptera (moths and butterflies), butterflies​ lay their eggs​ on host plants​, which​ hatch when the egg’s environmental conditions are met​ — usually 2-3 weeks later​.

One of the most effective products for getting rid of caterpillars is Monterey B.t., when applied correctly. Mix 1 to 1-1/2 Tbsp per gallon of water and apply when worms or caterpillars are first noticed, then repeat at five to seven day intervals while they are active. Apply thoroughly to top and bottom foliage​ and reapply after heavy rains. Pyrethrin ​sprays will also work well to control them.

One of our favorite pyrethrin products is Monterey Take Down, it ​​combines the fast knockdown of pyrethrin and the residual activity of canola oil. A natural alternative to Dursban, ​Take Down​ works on a large number of insects both indoors and out. Kills ALL stages of insects, including eggs and breaks down quickly in the environment. Although pyrethrin can have harmful effects on beneficial insects.

Hope this helps!