Spider mites on weed plants

Of all the possible invaders getting into your marijuana crop, spider mites on weed 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

Spider mites are so devastating to weed plants 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 on marijuana plants

Spider mites like your weed plants because they eat 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 weed 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 method you tried using.

Two-spotted spider mites are especially resilient to insecticides. They specialize in eating weed and are often called “the Borg” by marijuana growers.

Download my FREE marijuana grow bible and start growing high quality marijuana strains.

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.

It is always best to make sure that you give diseases or pest not even the slightest chance to find a place to stay among your plants. To prevent these issues, I have created a pack of three bottles which contents will make sure your plants get the best protection possible!

Marijuana plant protector

Bergman’s Plant Protector

  • Protect your plants from diseases and harmful pests.
  • Consists of three 20 ml bottles
  • Enough plant protection system supplies for up to 20 plants
  • Suitable for soil, hydroponic and all other grow mediums

Signs of spider mites on weed

Spider mites on weed 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.

Marijuana spider mites leaves

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 weed 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.

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 weed 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

Prevention of spider mites on weed

There are several ways you can prevent a major infestation of spider mites on your weed plants.

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.

spider mites on cannabis plants

Never bring in plants from the outside

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 weed plant from elsewhere, keep it under quarantine for a minimum of two weeks.

You can even check it with a handheld microscope.

Don’t let anything wander around in your grow area that shouldn’t be there

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.

How to get rid of a full-blown spider mite infestation on your weed plants

Firstly, ladybugs 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.

Using a hard water spray to get rid of spider mites on weed

First, use a hard water spray to hit your weed 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.

Using a vacuum cleaner to get rid of spider mites on weed

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.

Never simply assume it’s all over…

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.

It is always better to not have any issues in the first place of course! By using my Bergman’s Plant Food, created specifically for marijuana plants, you will ensure a great grow!

Other options to get rid of spider mites on weed

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 weed 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 weed plants), or insecticide.

Only use insecticide for extreme cases, and do it by treating your entire grow room with broad-spectrum insecticide.

Spider mites on cannabis plants

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.

Know how to perfectly time your harvest so you can maximize your yield. Download our free mini harvesting guide

Because spider mites like to stick around on weed 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.

Spider mite on weed – 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.

Are you experiencing more symptoms not listed above? Check out our full list of marijuana disease symptoms!

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 weed plants, then this is not a run-of-the-mill spider mite.

Instead, 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 weed plants with strong genetics have less chance of getting sick and are less vulnerable to pests and diseases. So make sure you get one of my grow sets, which will ensure a great grow and harvest!

FAQ about spider mites on weed

What causes spider mites?

The most common cause of spider mites is bringing plants from the outside into your grow room. You’ll also encourage a spider mite infestation if you let pets wander around, let dead leaves sit in your grow room, and expose your plants to high temperatures.

Do spider mites ruin weed?

Yes, they do. Spider mites eat chlorophyll, so plants can’t achieve photosynthesis. Worst of all, they have a high reproductive rate, making it possible for them to destroy many crops in a short time.

Can I use neem oil for spider mites on weed?

Yes, you can. Make sure you shake the plant before using the neem oil. Remember to exercise caution since neem oil is harmful to humans.

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

Happy growing!


Avatar for Robert Bergman

Robert Bergman


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

76 comments on “Spider mites on weed plants”

  1. Thank you, your information is a great read and I certainly will be trying your methods since I have an ongoing problem with spider mite. I’ve just done my fourth spray using a product called Nature’s Way, made by Yates. I live in Victoria, Australia and our summer has just started! I grew this plant from seed, like I grow all my seeds, my first two crops were bug free and my brother who lives in North Queensland, Australia always warned me of spider mites, this is the first time I have encountered them and and boy these little fuckers keep me busy! I’m interested in trying Green Cleaner but I’m not sure if it will be available in Australia, I’m just wondering if it’s not available here would you be able to suggest a match for Green Cleaner. Thank you, look forward to a reply.

  2. Apparently Neem oil (eco Neem) isn’t harmful to humans and only has the don’t use on food crops because the Australian government requires animal testing to have that removed from the label and this is something the Neem company aren’t willing to do . (Dogs need to be used and killed for results)

  3. Wow, this is a great article, chock full of info, and then there’s another treasure trove in the comments! Thanks everyone, I now consider myself an expert. 😉

  4. I had spidermite at the end of my last grow. I’m looking to go again and it’s been about 3 weeks.. I’ve cleaned my grow space best I can.. my questions are…
    Will the mites lay dormant in my grow space?
    How do spidermites get on the plants i.e do they climb up the side of the pot?
    I have a few methods in line to prevent them in the future but dont want to spend too much if they would of vacated the grow room after a few weeks.
    Thanks in advance and happy growing guys

  5. WOW this is very informative. We’re 1st time growers
    Our 1 and only plant is 5 1/2 months old we call her candy
    I just found a spider web on the poor baby
    I’m getting my vaccum out Right now she’s so big N beautiful I’d hate to loose her
    Ty for this information

  6. I have been finding web like material in my buds when I break them up. I don’t have any signs of any webs or bugs on the leaves or stalks. any idea what the problem is?

  7. Hi to all,
    I’m only 2-3weeks from harvest and I have definitely got spider mites,I plan to use neem oil and water. I will follow up with a pyrethrum treatment Or similar. My question is,will this damage the buds inanyway and will they be safe to consume. HELP!!!!?..

  8. 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) pointing so that mites will blow towards wall (not another plant). Afterwards, i laid a white piece of paper under the plant and should the hell out of it and only 4 mites fell off and they were not moving. I am using screen of green so its fairly easy to blow from under the canopy

  9. 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 them into our garden with a used grow tent that had been stored outside. I knew what was wrong with our plants as soon as I noticed spots and then the telltale webs. We currently have 27 plants and we will be moving 9 into our flowering room shortly. This is only our 2nd grow cycle, so we are just beginners. Just mix a quart of room temperature water with a Tbsp. of Dawn dish soap, in a spray bottle. Spray your plants, especially the underside of the leaves and the dirt. I repeated this every 2-3 days for a week, and all signs of the mites are gone and the new growth looks healthy. I also make sure that the ph of the water I use is 5.5 to 6.5. Good luck, I hope this helps.

    • 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. However; It is nice of you to share your success and give folks something to try. This is nothing new though, just so you know.

      Happy growing

  10. 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

    • 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 Food Grade only. You can dust the leaves all around and wait a week or 2 to harvest. The pproblem here is; Mite eggs willl hatch out in 2 weeks from killing adults. You have to deal with that too. The DE remnants will also kill the new mites but it will be a waiting game. Once you harvest rinse off the plants in the shower really good. Set up several good fans and fast dry the plant for a few hours until extra moisture and water has dissipated. Join us at support.ilovegrowingmarijuana.com for more ideas. Happy growing 🙂

  11. 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 40x magnifying glass to check. I purchased a 3 n 1 garden safe spray because I was reluctant to spray anything on the girls and the next day I saw some more thin strands of web. I however did not see anymore damage to the plant. I’m a first time grower and am very nervous about this. Do you have any suggestions? How long should I wait to either see more evidence of eradication or additional damage? The bottle instructs me to apply on a seven day schedule.

    • 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 would cull the grow and clean the room and start over. It would be better help to you to join our forum for advice from our friendly membership and staff experts.

  12. 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.

    • 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 your plants are so infested that you feel the need to dust the buds as well as the leaves (normally only leaf dusting is recommended), then your plants may already be too far gone.

      Thanks for your comment. 🙂

      • wish I read this before dusting plants. I dusted buds to prevent mites from invading. How log should I wait before washing off DE

  13. 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. Soak buds in tub and monitor for floating particles. after a few minutes, skim the mites and debris off the top, remove your buds and hang them in an areas with many fans to dry them quickly. Good Luck.

    Perhaps joining the ILGM support forum would be a good idea, too 🙂

  14. 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 still SM. Now drying, and soon ready to partake. Tried 10-5 sec in microwave…but still some SM. Any more suggestion? Will they die off when thoroughly dry? Help…

  15. 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 of day when light is dimmer. Less uptake occurs in lower light periods. I would think you would be gently wiping the solution across all leaf surface.

  16. 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

    • 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 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 of the DE.

      Do not use Pool grade DE!

      hope this helps


  17. 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

  18. 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” 🙁

    • 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 of the DE.

      Do not use Pool grade DE!

      hope this helps 🙂


  19. The babies will come back above referres to the baby plants
    You can dip the plant into the above solution when ever possible. Enjoy

  20. 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 plants underside leaves 3 times every three days and then examine the plants for signs with a loop and flashlight Remove any very damaged leaves and discard The mites and eggs will be gone after the third application Baby’s will come back The problem will reduce you total yield which is always disappointing I did not wash the plants down after the application Just left it on to dry The mites will be a black (a dead dot ) when killed Gray with two spots when alive in my case Enjoy
    My sign that they are present is the leaves start to curle under so I do see them early on which is a big advantage After the procedures the plants held up very well so all good

  21. Broad mites and/or russet mites are by far way worse than spidermites. Broad mites are the undisputed king of pests.

  22. 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 leaves and then drench the rest of the plant with bright lights and fans off.
    Spray water 7 to 8 hours later to rinse then run fans before grow lights come back on.

  23. Does anyone know of any natural sprays for russet mites,hard to find info anywhere like their a new kind or something

    • 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 awesome…

  24. 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 bad…once in a while thing! 😉

    • 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. Soak buds in tub and monitor for floating particles. after a few minutes, skim the mites and debris off the top, remove your buds and hang them in an areas with many fans to dry them quickly. Good Luck.

      Perhaps joining the ILGM support forum would be a good idea, too 🙂

  25. 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 with pincher…one escaped/hide in hoz poz…. I used neem oil for no effect it still roaming ..playing hide & seek…so I used insecticide I brought home to kill termites! voilla! Time tested dead on spot mechanism!… LOL

    Hope it must be dead somewhere…kinda very effective spray on termites and other pest np!… seen it in action…don’t take more than 1-2 sec to kill a big ant… Anyway raising plant for somebody else….deadly ppl they are…jadiyals we call……lil pesticide wont hurt them! 😉

    Rather lil poison wud make them more immune to such things…then they already are! Saale ne mujhe clove pilai thi mein pesticide pilaunga phatichar ko! Sure I dont care as well for myself…got high connections with gods LOL


    • 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 budding- big mistake! I’ll try the DE. Any concerns with this staying on the bud after harvest?

  26. 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 didn’t follow the instructions in the grow guide.
    I treated them with rosemary tea about three weeks ago but they are back of course.I am going to try the bleach and vacuum since I am so close to harvest . Needless to say once I have harvested my entire grow room will be sanitized. I guess those are lessons you learn. Any suggestion is welcomed but I am going to just try following the instructions better!

  27. 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 to over dry. This seems to have killed them. I then removed my young ones and fumigated my room. I treated my little ones with Neem oil. I am crossing my fingers as this is an experiment.
    Ant thoughts?

  28. 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 vaporizer or humidifier

  29. 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 , lined the rim’s (and or) water trays with ” TREE TANGLEFOOT” never bothered again !!!
    IMPORTANT keep all leave’s away from side wall’s or shelve’s

    Hope this idea helps other’s , worked for me !!!

  30. 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 to82 veghumidity 60 bud 35 to 45 u dont want water in the air when you flower you might need a dehumidifier there about 150 170best of with both humidifier when vegin an vi versa u will get mold if you keep humidity higher like 50 60 and u wount c it it starts from the insideout mold so watch that humidity as well as that heat get a 2 in 1 meter there cheap peace im out aka sanesaint420

    • 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?