What are Spider Mites?
Spider mites are members of the mite family Tetranychidae. Spider mites are less than 1 mm (0.04 in) in size and vary in color. They live on the underside of leaves, laying small, round eggs and spinning silk webbing to help protect the colony from predators, hence the name “spider” mite.
Spider mites feed on the chlorophyll in the cells of leaves, damaging their ability to use photosynthesis. They are known to feed on several hundred species of plants, including Cannabis sativa.
Under optimal conditions (~ 80.6°F or 27°C), one female mite can lay up to 20 eggs per day and can live for 2 to 4 weeks, laying hundreds of eggs.
This fast reproductive rate allows spider mite populations to adapt quickly to resist pesticides, so chemical control methods can become ineffectual with over-use or with repetition over time.
Treating a Spider Mite Infestation with Organic Methods
Effectively killing spider mites starts with good spider mite detection. Good spider mite detection starts with looking at your plants.
3 common signs of spider mites on cannabis plants include:
- Yellow, tan or white spots on the plant’s leaves.
- Very small white or red moving spots on the leaves. These are the mites, though you might need a magnifying glass to see them.
- White, cotton-y webbing that appears mainly on the underside of the leaves, though webbing can appear on other areas.
If you believe that any of your hemp plants are affected by spider mites, immediately isolate the plants, and take steps to kill the spider mites.
Plant Pruning & Care — Prune leaves, stems and other infested parts of plants past any webbing and discard in trash or burn them in a safe/legal manner (do not discard affected leaves in compost piles). Don’t hesitate to pull entire plants to prevent the mites spreading to their healthy neighbors.
Natural Oils & Topical Treatments — Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. GrowWeedEasy.com has a comprehensive list of treatments and organic, cannabis-safe sprays, soaps etc here >> How to Get Rid of Spider Mites
Beneficial, Predatory Insects — Commercially available beneficial insects are important natural enemies. For best results, make releases when pest levels are low to medium.
Beneficial insects that eat spider mites include:
- Lady Bug (Stethorus punctum). Known as the spider mite destroyer or black mite destroyer
- Lacewings. (Watch a lacewing larvae eat spider mites)
- Predatory mites. (Watch Applying Predatory Spider Mites to your cannabis plants)
Preventing a Spider Mite Infestation
Hot, dusty and dry conditions are often associated with proliferation of spider mites.
- Water sufficiently to avoid water-stressing or drought-stressing your plants. Poor irrigation can make plants more susceptible to mite infestations.
- Keep dust to a minimum. Dust on leaves and branches encourages mites. Use ground covers or cannabis mulches, and irrigate regularly.
- Cool environment & air circulation. Spider mites prefer the heat and hate a windy environment. A cool breezy grow space won’t kill the mites, but makes it harder for them to reproduce, as they cannot mate in windy conditions.
- Diatomaceous earth. Sprinkle on top of the soil around the plants. It’s harmless to people, critters, and other plants but is microscopically sharp and can injure and dehydrate mites on contact. This won’t stop an infestation, but can slow it down.
- Growing Smart: Be attentive to your plants and their needs and try to stay ahead of detrimental seasonal or environmental factors that can encourage pest growth in your cannabis crops.
- Growing Organically: Using harsh chemical products to deal with cannabis plant pests can potentially be harmful to you, your workers, and your pets or livestock. Here is a list of some safe and effective techniques and repellents from ILoveGrowingMarijuana.com to get you started!
Additional Resources for Dealing with Spider Mites
UC IPM (University of CA): Spider Mites
GrowWeedEasy.com: How to Get Rid of Spider Mites
Disclaimer: Clone Connect does not sell marijuana. All marijuana-related content is for informational and educational purposes only and intended to help our users understand the difference between marijuana and industrial hemp.