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Of all the possible invaders getting into your marijuana crop, spider mites are by far the worst. They’re a common cannabis pest, and can be hard to get rid of.

Spider mites are not actually insects, but rather arachnids (like spiders) since they have eight legs and lack antennae. They also have an oval-shaped body and are related to ticks and other mites. They are called spider mites because of the web that they spin on your plants’ leaves and flowers.

 What are spider mites

What are spider mites on weed plants

Spider mites are so devastating simply because of their extremely high reproductive rate. Eggs hatch in just three short days, and five days after that the spider mites have reached sexual maturity. At this point, they will begin reproducing rapidly. A female spider mite could lay millions of eggs in one month. Do you see the issue here?

Spider mites like your marijuana plants because they eat the chlorophyll, the substance all plants need to achieve photosynthesis. They have little teeth that bite into one plant cell and remove the chlorophyll. Imagine that happening from millions of spider mites at one time – this is how entire crops are destroyed.

Spider mites can appear in any setup, but they are less common in hydroponic growing systems. They are especially common in soil because there is more dead organic matter.

Spider mites can destroy your plants at an incredibly rapid speed. Bad infestations have been known to actually kill a plant overnight. They also are extremely adaptable, and they grow immune to your method of killing them. This happens if your method hasn’t worked completely, and some spider mites were left. Then you will soon end up with an army of super spider mites that are immune to whatever you method you tried using. Two-spotted spider mites are especially resilient to insecticides. They specialize in eating marijuana and are often called “the Borg” by marijuana growers.

Download my free marijuana grow guide at this link for more growing tips

The spider mite life cycle is what makes them so resilient as a species. When adult females lay their eggs, they will hatch within a few days (or sometimes weeks). The hatched organisms are called larvae, and they have round bodies with three sets of legs instead of four. These larvae will feed on your plant for several days until they choose a spot that is protected or sheltered and then molt, thus entering their first nymphal stage. This first nymph has four sets of legs instead of three.

A first nymph follows a similar pattern: it eats for several days, then finds somewhere to rest and mold into the next phase – the second nymph. The second nymph follows the same pattern. It eats for a few days, rests, then molts into the final adult stage. They have thus reached sexual maturity.

Male adults remain roughly the same size as a second nymph, and their abdomens are pointy. Females’ abdomens are round, and they are larger than males.

Due to this unique life cycle, if you kill off all the adult spider mites then you might think you have eradicated the problem altogether. Unbeknownst to you, the less mature spider mites could still be happily chomping away at your plants, about to enter their own adult stages of life.

Signs of spider mites

Signs of spider mites on weed plants

Spider mites can be tough to notice right away, making it difficult to get ahead of the game when it comes to eradication. They will appear like little dots to the naked eye, no bigger than the tip of your pencil lead. Many growers don’t notice that there is anything off until the infestation is big enough that it’s impossible not to see.

This is why it’s extremely important for you to do routine leaf inspections. Check both sides of the leaves to see any spider mite damage. Do this often, because you will need to have enough time to act faster than the speedy spider mites.

Spider mites generally live on the undersides of your marijuana plants’ leaves. Much like a “normal” spider, spider mites spin a web to keep their eggs and colony safe. You should be able to notice when a spider mite is making its home beneath a leaf because you will see fine white strings between leaves.

Download my free marijuana grow guide at this link for more growing tips

If you do, you will know there’s a problem to be dealt with. You also might see the fine silk on your plants’ foliage. This sticky silk will collect dust and dirt and will make your plant look dirty. It is especially common in a flowering room to see buds covered in this fine webbing.

The first signs of a spider mite problem will be seen on the leaves. Tiny specks will begin appearing – these specks are actually little bite marks from where the mites took a chomp of your plant. These spots might be yellow or white in color.

If a plant is badly infested with spider mites, the whole thing will start looking sickly and discolored, and could eventually just die. Not sure if spider mites are causing the damage to your marijuana plants? Check the article Marijuana pest and bug control for a list with pictures of all pests and bugs

How to get rid of spider mites

Get rid of spider mites on cannabis plants

There are several ways you can prevent a major infestation of spider mites. If you use an organic compost mulch, for instance, you will be unknowingly adding predatory mites to your plants’ defenses. These beneficial mites eat the spider mites.

Other tips for prevention include never bringing in plants from the outside into your grow room. This is the most common cause of a spider mite infestation. If you have an external clone or a marijuana plant from elsewhere, keep it under quarantine for a minimum of two weeks. You can even check it with a handheld microscope.

You also shouldn’t allow old, dead leaves to sit in your marijuana grow room – ever. Pick up any dead leaves on a regular basis and put them in a totally new location. Just make sure you move them out of the grow room! Cleanliness is also key – don’t ever walk into your grow room straight from the outside; ensure your cleanliness first. Don’t let any pets into the grow room, and keep the airflow nice and consistent.

If you have air coming in from outside, apply a filter of some kind to keep bugs out. It’s best to start your crop out with seeds instead of clones, especially if you are only growing for personal use. Keep temperatures on the lower side, since spider mites love the heat.

Download my free marijuana grow guide at this link for more growing tips

Ladybugs also eat spider mites, although if you purchase them they will fly away as soon as their source of food is gone, so they don’t work as well preventatively. They often show up to your crop naturally when you have a spider mite problem, in which case you don’t need to buy any ladybugs. Mother Nature can be awfully helpful sometimes.

If you were unable to prevent an infestation from occurring, there are a few steps you can take to handle the problem before it destroys all of your plants. First, use a hard water spray to hit your plants, three mornings in a row. The water pressure alone should take care of the bugs and their webs. They will fall to the ground and, unable to move anywhere else, will eventually die from lack of food.

A commercial product like Bug Blaster will always to the job. If you want to make sure to kill them all buy something like Bug Blaster.

Another option is also deceptively simple. Try using a handheld vacuum cleaner to simply suck the mites straight off of your leaves. This takes a bit more time, but should be an effective way of removing the mites. You should then carefully put the contents of the vacuum into a sealable plastic bag, then put that bag into the freezer. The mites will die from the cold since they live in higher temperatures. Then simply get rid of the bag with the rest of your trash on garbage day.

One potential problem you could run into is an apparent resurrection of the spider mites. This is every marijuana grower’s worst nightmare. Of course, it is not actually the same spider mites coming back to life. It is actually their millions of eggs that all hatched within a few days or weeks of when you thought you had gotten rid of these pests. If you bought ladybugs to take care of the problem, this could occur after they have already flown away in search of more food. You will have to use a different method or buy a new set of ladybugs – but you better do it quickly!

You can also go to your local gardening center and see what sprays they have to get rid of the mites. An additional option is to use neem oil. You should shake your plant and then kill them with neem oil or another product that will kill the spider mites on contact. Be careful with the neem oil, however, as it can harm humans.

Download my free marijuana grow guide at this link for more growing tips

Some other options are using a bleach solution  made of 1 tablespoon of bleach to 1 gallon of water that is 95 degrees Fahrenheit and pH balanced), or alcohol and water (30% or more of the solution should be water to avoid hurting the plant itself). You could also make a homemade pepper spray (9 parts water, 1 part dishwashing soap that doesn’t have any additives, 1 tablespoon of cayenne pepper), nicotine tea (15 grams of organic tobacco, steep with hot water overnight), dichotomous earth (fossil dust that can be sprinkled over your plants), or insecticide. Only use insecticide for extreme cases, and do it by treating your entire grow room with broad spectrum insecticide.

Please note: Anything that contains Abamectin or Lindane is harmful to humans. Make sure you know what is in your treatment and proceed with caution.

After two or three days of using one method, follow up with another method as well as re-using the original method. Repeat the entire process one more times – or more! Once you think you’ve taken care of the spider mite problem, treat the area a minimum of one more time.

Because spider mites like to stick around and resurrect their numbers after you have treated your crop already, make sure that you continue treating after the infestation appears to be gone. Always assume they are hiding away, preparing secretly to destroy your plants as soon as you turn your back. Kill them before they can. Use multiple methods when you are exterminating the spider mites so that you can ensure they all die. Constant, varied attacks are the best way of handling this mighty foe.

Marijuana plant symptoms

Leaf Symptoms:
– Brown, dark spots
– Mottling or mosaic pattern
– Slowed growth
– Webbing on leaves

Plant Symptoms:
– Slowed growth
– Wilting or drooping of plant
– Bugs
– Buds not fattening

If you’re growing indoors, it’s important to determine where exactly your spider mites came from. This is a good thing to do before you start using everything in your power to destroy them.

Were the spider mites just randomly brought into your grow room from the outside? They could have come from a vegetable garden, from animals or your pets, or from another plant that isn’t marijuana. If they were just tracked in from outside, they most likely they are your standard non-super spider mites, so you can go ahead and use a simpler home remedy to take care of them.

If, however, they came from another marijuana grower, you may have a tougher time killing them. If they came from clones you used, or maybe were somehow tracked in from someone else’s marijuana garden, or any other situation where the spider mite was living on someone else’s marijuana plants, then this is not a run-of-the-mill spider mite.

This is a marijuana expert. If they are two-spotted spider mites, you will have a very difficult time with them. They are probably already immune to lots of eradication methods. You should, therefore, use the strongest remedies immediately. Don’t wait around and play games, or your entire crop could easily get destroyed.

Remember that plants with strong genetics have less change of getting sick and are less vulnerable for pests and diseases. So make sure to buy cannabis seeds from a trusted seed bank.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible

Robert

The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]

60 Comments

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  1. By WILL DEBUDEY

    ,10 Oct 2013
    HOW LONG CAN YOU VEG FOR TO GET GOOD RESULTS . I HEAR 4 WEEKS UP 8 WEEKS WHITCH ONE IS IT FOR YEILD THAT IS THANKS ..
  2. By george

    ,16 Nov 2013
    Just wanted to say thanks for the info and please keep up the good work
  3. By sanesaint420

    ,20 Dec 2013
    first of all you really must put time mony and your hart into growing u do that u can do it buds that have resinglands u wount even need a magnafieglass to see them do some reading tip heat 75 […]Read More
    1. By Tengolor

      ,13 Dec 2015
      Not a single punctuation, mark and terrible spelling. I'm sorry, but how on earth do you ex.pect anyone to understand what you have written?
  4. By Tron

    ,09 Jul 2014
    High, I'm very new , given 2 cropped plant's to grow. Yes the dreaded spider mite turned quickly to full bore mite's !! Killed all twice but, returned. Thought and thought about a defence. Since Spider Mites are ground crawler's […]Read More
  5. By Douglas

    ,07 Oct 2014
    Lady bugs will only work in a controlled environment. And even then they fly into light and die. It's important to gain control early on outdoors. The best I've used indoor is Forbidden. Only in early stages better used with […]Read More
    1. By holly

      ,18 Jul 2017
      do you mean put solution in the vaporizer?
  6. By herbedmonds

    ,17 May 2015
    I was given the lovely gift if mites as my plants were ready to harvest. I finally tried cooking my harvested plants at 170 (the lowest my oven would go) for a few minutes at a time, being careful not […]Read More
    1. By latewood

      ,23 Sep 2015
      I suggest you join our support forum and introduce yourself to many more support options. I do not like Neem Oil. I use: Diatomaceous Earth - Food Grade CODEX, to control Spider Mites, and other soft exoskeleton pests http://www.amazon.com/Diatomaceous-Earth-Food-Grade-10/dp/B00025H2PY/tag=greenrel-20
      1. By VintheHouse

        ,29 Oct 2016
        Doesn't the diatomaceous earth get into the flowers and stay visible?
        1. By Richard

          ,10 Jan 2019
          Agreed, Don't think you'll ever get that shit out of the buds... ??
  7. By Symptom Checker – Identify Marijuana Plant Problems

    ,24 Jul 2015
    […] Spider mites […]
  8. By Terry

    ,19 Sep 2015
    Hi, Thanks for all your info this is my first grow . I have found your guide quite help full. I am about 2 to 3 weeks from harvest. Beautiful buds but all at once spidermites. My fault because I […]Read More
    1. By holly

      ,18 Jul 2017
      rosemary tea? how did you use it?
    1. By Rita

      ,24 Sep 2016
      Also, I purchase my food grade diatomaceous earth from Earthworks, they have a great deal on 4 gal. sized jugs. My grow tent is infested with spider mites, one plant almost dead, had brought 4 in from outside to prompt […]Read More
      1. By Rita

        ,28 Sep 2016
        I answered my own question- DE rinses off the plants- I knew that...duh..
        1. By VintheHouse

          ,29 Oct 2016
          It rinses off, but wouldn't a flower with all its nooks and crannies and sticky tricombs hold it in?
  9. By Nick

    ,28 Oct 2015
    I got a single plant ...female it is I suppose bt we call it male here in local (which forms seeds)...My plant just started forming flowers two days ago...and I saw few spider mites....4-5 mites...I killed 4 out of them […]Read More
  10. By Nick

    ,28 Oct 2015
    But sure guys I don't recommend it for others to copy cat...apni baat alag! Apni toh life bhi alag hjai saare globs se! ;) Actually I dont recomend even marijuana at all but tasting for curiosity or occasional fling not […]Read More
    1. By latewood_ILGM

      ,05 Aug 2017
      sicilianpie, I am afraid it is too late to do anything. I will offer one method to try. Get a big tub 15-20 gallons, and fill with water, add hydrogen peroxide to the tub of water. A cup will do. […]Read More
  11. By Stop Aphids On Marijuana Plants Now!

    ,01 Dec 2015
    […] spider mites, aphids are happiest at a temperature between 60 and 80 degrees Fahrenheit. When they snack on your […]
  12. By jb

    ,08 Jul 2016
    Has anyone had broad mite problems, and if so, how do you get rid of the pesky little bastards?
    1. By Discountdan

      ,03 Oct 2016
      Broad mites and russet mites The best thing I have used that lived up to killing them is a product called "Wipe Out" Saved my crops for sure after one application of the ready to use product. That stuff is […]Read More
  13. By Greenpheenrp

    ,28 Aug 2016
    Does anyone know of any natural sprays for russet mites,hard to find info anywhere like their a new kind or something
  14. By Greenpheenrp

    ,28 Aug 2016
    Anyone know any good cure for russet mites?
    1. By Roy ILGM

      ,29 Aug 2016
      Hi Greenpheenrp, the short answer is repeated spraying of neem/pyrethrum/canola oil but there's more to it. Our support forum has better formatting to handle your question. Best to post your question there.
  15. By Jacko

    ,29 Aug 2016
    Try in a half gallon solution with a 1 gallon sprayer - 6 tablespoons of hydrogen peroxide 3%, 4 table spoons of 70% or 90% rubbing alcohol and 1 teaspoons of Dawn or non-bacterial dish soap. Spray under all the […]Read More
    1. By Jasna

      ,06 Jul 2017
      Will turning the lights down for so long stress the plants out?
  16. By Nic moore

    ,01 Oct 2016
    Broad mites and/or russet mites are by far way worse than spidermites. Broad mites are the undisputed king of pests.
  17. By Reefer man

    ,14 Dec 2016
    Jacko Aboves 1/2 gallon mix kills on contact I added 2 tsp of mineral oil to his mix to keep the mixture on the plant surfaces longer It worked great I had the black spotted kind Need to soak the […]Read More
    1. By tbob

      ,13 Feb 2017
      sounds like the 1989 bug oh bad hard to deal with
  18. By Reefer man

    ,14 Dec 2016
    The babies will come back above referres to the baby plants You can dip the plant into the above solution when ever possible. Enjoy
  19. By Doug

    ,29 Dec 2016
    Wish that I would have read to start with, just lost $500.00 to spider mites. 14 plants!!!! From now on I will read daily and inspect daily!!!! You do have great information! This "was an indoor grow" :(
    1. By Roy ILGM

      ,29 Dec 2016
      Sorry to hear Doug! I hope your next grow will bring you many delicious buds!
    2. By latewood_ILGM

      ,13 Mar 2017
      For eradication of Spider Mites; Look into Diatomaceous Earth Food Grade. Dust plant and miters die off sue to being scratched and dehydrated. You have to be patient because SM eggs will hatch and will have to also be victims […]Read More
  20. By tbob

    ,13 Feb 2017
    what does anybody know about megawash i find that it can leave a white spark when smoking anybody have this problem i won t use it anymore
  21. By John (Australia )

    ,11 Mar 2017
    Hi I've got a spider mites 6 weeks into bud I've just found a prayingmantis on my plant my eating away happily anything else I can use to get rid of the mites greatly appreciated
    1. By latewood_ILGM

      ,13 Mar 2017
      John, It is pretty cool you have a praying Mantis working in your garden. They only hang around if they find food. :) Here is what I use. Happy growing! :) For eradication of Spider Mites; Look into Diatomaceous Earth […]Read More
  22. By Jasna

    ,06 Jul 2017
    How long do the lights need to be out for applying the alcohol solution?
  23. By latewood.ILGM

    ,11 Jul 2017
    Jasna, Personally, I would not use the alcohol method. I cannot imagine the plants responding well. On the other hand; We are always surprised by the process of science in relation to nature. I would think in the latter part […]Read More
  24. By sicilianpie

    ,30 Jul 2017
    I am new to growing. I was ready to harvest when upon inspection with loop, I see what I believe are spider mites. I hosed washed then cut the plant...but now what should I do? Still there. I vacuum buds...but […]Read More
  25. By latewood.ILGM

    ,05 Aug 2017
    sicilianpie, I am afraid it is too late to do anything. I will offer one method to try. Get a big tub 15-20 gallons, and fill with water, add hydrogen peroxide to the tub of water. A cup will do. […]Read More
  26. By firstlegalcrop

    ,14 Sep 2017
    I do not think dusting with DE would be a good idea if plants are budding and sticky. I don't want that crap in my lungs. I really doubt it will rinse off.
    1. By latewood_ILGM

      ,20 Sep 2017
      DE is edible and totally safe for humans. I would not want to smoke it wither. However; It does work, and if you wash your plants in the shower rerally well, it does rinse off. On the other hand; If […]Read More
      1. By RoyC

        ,18 Nov 2018
        wish I read this before dusting plants. I dusted buds to prevent mites from invading. How log should I wait before washing off DE
  27. By Ben

    ,31 May 2018
    I have three week olds and noticed one section of leaf that developed small clusters of white dots. I have thin web strands in between leaves but I have not seen anything on any of the leaves. I used a […]Read More
    1. By latewood_ILGM

      ,06 Jun 2018
      Ben, Does the bottle of 3in1 say it will kill spider mites? I use food grade Diatomaceous earth. Get a garden duster and add some DE and sprat the underside of leaves and room with the dust. (lightly). Otherwise; I […]Read More
  28. By Buck

    ,16 Aug 2018
    I’m on day 51 of flowering out of what should be 55 days. Noticed spider mites when checking the trichomes. Its 8 ball kush and just getting a few amber trichomes. Need advice
    1. By chronic

      ,17 Aug 2018
      buck i advise take that bi*ch down
    2. By craig

      ,17 Aug 2018
      i advise take that bi*tch down dont want to end up with web buds for the sake of 4 days
    3. By latewood_ILGM

      ,21 Aug 2018
      Buck, One way or the other, you need to get rid of the mites. You could harvest but, the mites are still going to be there. Do not use neem oil this late. I would consider a dusting Diatomaceous Earth […]Read More
  29. By Christi and Carl Austin

    ,10 Nov 2018
    I just wanted to let you know the simplest and cheapest way to rid your garden of spider mites. I have used this with house plants and now on our indoor cannabis garden with great success. I believe we brought […]Read More
    1. By latewood_ILGM

      ,14 Nov 2018
      Christi and Carl Austin, Thanks for sharing. I am glad you had such good luck. This is a method that has been tried for a long time by many, many growers. Most of the time, it does not eradicate mites. […]Read More
  30. By Bobby B

    ,26 Mar 2019
    To get rid (or at least control the hell out of) spider Mites, I used ANZ twice at 5 day interval then Next Day used my electric leaf blower and hit all plants for a few quick blasts (on low) […]Read More

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