Spider Mites on Weed: Guide to Finding and Killing Them

Spider Mites

Table of Contents

Of all the pests that invade cannabis plants, spider mites on weed are the worst kind. These pests are resilient and are very hard to remove. Just when you think all your efforts are working, these pests are still somewhere lurking nearby. 

What are Spider Mites?

Spider mites are not insects but are a member of the spider family and are called arachnids. They resemble spiders as these have eight legs and don’t have any antennae that common insects have. Use a magnifying glass and you’ll notice that spider mites come with flat and oval bodies just like ticks and mites. These are called spider mites because they behave like spiders as they can create thin webbing to cover plants and buds.

Why are Spider Mites on Weed very Resilient?

Spider mites are a nuisance to cannabis as well as other plants because they reproduce very fast. The spider mite eggs will hatch in just three days. Add another five days and you’ll get spider mites that are ready to reproduce. 

A single female spider mite can lay a million eggs in a month. Also, spider mites in a plant are in different stages of life. You might find mites laying eggs in one area of your plant and young mites on the other. In short, a pest control product meant to destroy only the mites won’t be as effective. Spider mite treatments will need to be provided throughout the growing or flowering phase to be very effective.

Spider mites eat chlorophyll in plants. This is a compound that plants need to make their food. The small teeth of these mites bit through the plants’ cells and suck up all the chlorophyll. When thousands or tens of thousands of spider mites strike and bite the chlorophyll out of your plant, all your hard work may be destroyed in just one night. 

Spider mites often affect cannabis plants that are grown in soil or from the ground but are less common in hydroponics growing systems. These pests are found mostly in the soil as these have more decaying organic matter in them.

Spider mites can eat weed plants quickly. The worst infestations can kill a healthy plant overnight! Another reason why spider mites are hard to remove is that these can adapt quickly. This will happen if your pest control method works slowly and you are not able to completely eradicate all the mites in your garden. 

If this happens, you will have spider mites that are immune to the product you are using. These pests can develop resiliency in almost all kinds of insecticides. 

How to tell if your Marijuana has Spider Mites?

It’s hard to tell at first if your cannabis plants are affected by spider mites. These pests will first appear like very small dots, the size of a pencil head. It’s hard to tell they are there until there is an infestation and they are very hard to remove. This is why routine leaf inspections are necessary. You must check the outer and inner part of the leaf to check if there are spider mites and if there are small bite marks. You should inspect daily or two or three times a day especially when you’re growing in soil medium

Spider mites prefer to eat and live along the undersides of leaves because these are softer and juicier. Spider mites spin webs to protect their eggs and their colonies. If actual mites are hard to see as they are microscopic, the presence of webs at the bottom of the leaves is enough to tell that there are spider mites on your weed. If you discover web or fine strings that connect leaves then be ready for an infestation. 

Check for the following

  • Fine silk all over your plants, buds, and leaves. The web collects dust and dirt and makes your plants appear dirty.
  • Specks are on the leaves. These are very tiny bites made by spider mites. The bites can become white or yellow.
  • Your plants will look very sick and discolored. Your plants may also die as it won’t get any food from the leaves as spider mites have already sucked all stored chlorophyll.

How to remove Spider Mites effectively?

We will divide spider mite removal treatments into natural and chemical methods.

Natural Pest Control Methods

1. Use Water Spray

Fill a spray bottle with water and aim for the spider mites. For this method to be effective, take your plants outdoors and spray away. Use a jet-like stream that will instantly detach the mites from the leaves and stems. Don’t forget to spray on all plant parts over and under the leaf surfaces. Repeat this method as necessary. 

2. Use a Vacuum Cleaner

A vacuum cleaner at the medium or high setting will suck up all the pests and eggs from the surface of the leaves and stems. Use a telescopic tool attachment to better reach all the parts of your plants. Once you’re done with a plant, remove the filter and empty it from afar. This should be far from your growing area. Do this as often as you can. You may also sweep the folds of your cannabis buds and even on the soil or ground surface to remove any mite or eggs that may have fallen from the plant body. 

3. Water and Soap Solution

Instead of just spraying water, spray a combination of water and soil. This will help dislodge the mite and eggs from the surface of the plant and will also soften the hard outer shells or bodies of the mites to make them more vulnerable to other chemical pesticides. 

Water and soap solution is easy to use and is readily available since you can use bath soap or dish soap in your kitchen. Also, this method is safe to use and won’t’ harm you or your plants. You can use this natural method while your plants are in their growing phase to the blooming stage.   

5. Add a Fan- Create a Windy Environment

Spider mites love warm environments and will thrive well in still plants. The movement will make it hard for these pests to reproduce and lay eggs. Therefore, you can add a fan to blow constantly over your plants. 

Aside from removing pests, the wind will also help grow strong and branches and stems which will help your plants hold heavy and dense buds. 

6. Use Predatory Mites and Insects

There are bad insects such as spider mites and there are good insects too such as ladybugs. These bugs also have voracious appetites and spider mites are a part of their menu. You can order ladybugs in packs and just place them all over your garden.

The downside of using predatory mites is that these insects also have short lifespans and may not last long until all the spider mites are gone. Therefore you should replace predatory bugs populations after a few days.

To effectively eradicate spider mites, you must combine natural treatment with chemical pesticides. A combination of three or four treatments at the same time can help reduce the number of spider mites effectively. 

Chemical Pesticides to Kill Spider Mites

These are the most common chemical pesticides available in the market that can kill spider mites and other common cannabis pests. 

1. Azamax

Azamax is one of the most effective chemical products that can kill pests including spider mites. Use Azamax 15 minutes before you power off your grow lights. Spray liberally all over your plants especially on top of the soil.  

Dry the area using a fan. Continue to spray Azamax for days or weeks after you don’t find any more mites. Add Azamax to the water you use to water your plants. These won’t hurt soil but will kill spider mites in soil. 

2. Spinosad

Spinosad is one of the most effective but safe and organic. It is harmless to pets, plants, and people. You can use this to directly kill spider mites or mixed with water to kill mites in the roots. And aside from spider mites, you can also use Spinosad to use other pests like caterpillars, crickets, and thrips. 

Take note that most Spinosad products are effective for only 24 hours after you prepare it with water. Therefore, mix only the amount you will need, any leftover will only be thrown away. 

3. Organic Essentria IC3

You can use Essentria IC3 to kill spider mites. This product is made from a mix of organic horticultural oils that are deadly to pests but are safe for humans. This is usually branded as a bed bug killer but can be effective in killing different pests like spider mites.  

The problem with Essentria IC3 is that this is effective only in plants for up to 12 hours so you must apply this daily or use it with other methods. 

4. Doktor Doom Spider Mite Spray

Doktor Doom Spider Mite spray is very effective on spider mites. The main ingredient of Doktor Doom is pyrethrum which is not too good for plants that are grown indoors. Also, this treatment kills only the bugs but not their eggs therefore you will need to use this with other methods.  

Pyrethrum must be used only as the last resort. It is effective for spider mites but may be harmful to other garden-friendly insects like bees and ladybugs.

5. Floramite

Just like Doktor Doom, Floramite is very effective but may contain harsh chemical components that may be dangerous to plants and humans. Also, Floramite is very expensive so use this only when all other methods are not effective. 

6. Pest Strips

Pest strips are effective in trapping and killing spider mites but the fumes from these strips can be harmful to humans and other animals. 

7. Neem Oil

Neem oil is an oil that comes from the neem tree and is very effective as a pest control treatment. This is diluted in water and sprayed on all the plant parts but not on the buds as this has a very strong and unpleasant smell. Use neem oil carefully as there is evidence that this is harmful to humans. Use masks and gloves to protect yourself. Spray neem oil and water on all the parts especially on the leaves. Spray once or twice a day and soon, spider mites will be killed and infestation under control. 

8. Diatomaceous Earth

Diatomaceous earth is fossil dust and it may look like dust to humans but for small pests like spider mites, these are very sharp, jagged pieces that can slice through their bodies and kill them. You can buy diatomaceous earth from garden shops. Just sprinkle this all over your plants and on the ground to control spider mites and other pests.

How to Prevent Spider Mites?

1. Use Organic Compost Mulch

Organic mulches contain predatory bugs that can help you fight pests especially spider mites. These pests will eat these bugs and thus prevent any infestation. You can buy organic compost mulches from garden shops locally or online.

2. Don’t Bring a New Plant in

Take note of this simple way to prevent spider mites. Taking a new cannabis plant or clone inside your growing area can bring in spider mites that have been treated by other types of pesticides, natural or chemical. There is a huge chance that these bugs will be resistant to the treatments you provide. Meanwhile, if spider mites are from other plants like flowering plants or vegetable plants then these mites may not be resistant to pesticides and hence, may be easy to get rid of. 

So to avoid spider mites altogether, quarantine a new plant before introducing it to your garden. 

3. Avoid Bringing any Pests inside the Growing Area

If you have an indoor area, avoid taking pests and other things inside by leaving your footwear outdoors. Wear gowns, masks, or gloves. Avoid pets and children inside the growing area.

Spider mites in weed are a challenging thing to remove. It’s hard to remove and is very resistant to regular pest control products. We recommend using different kinds of products and pest control methods to completely eradicate spider mites.

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