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Spider Mites On Marijuana Plants

Spider Mites On Marijuana Plants

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


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Comment Section

49 thoughts on “Spider Mites On Marijuana Plants

By WILL DEBUDEY on 10 October 2013


By latewood on 23 September 2015

That’s right!

By george on 16 November 2013

Just wanted to say thanks for the info and please keep up the good work

By sanesaint420 on 20 December 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 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

By Tengolor on 13 December 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?

By Susan Rowell on 9 January 2014

thank you

By Tron on 9 July 2014

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 !!!

By Douglas on 7 October 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 vaporizer or humidifier

By holly on 18 July 2017

do you mean put solution in the vaporizer?

By herbedmonds on 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 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?

By VintheHouse on 29 October 2016

Doesn’t the diatomaceous earth get into the flowers and stay visible?

By Terry on 19 September 2015

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!

By holly on 18 July 2017

rosemary tea? how did you use it?

By Rita on 24 September 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 budding- big mistake! I’ll try the DE. Any concerns with this staying on the bud after harvest?

By Rita on 28 September 2016

I answered my own question- DE rinses off the plants- I knew that…duh..

By VintheHouse on 29 October 2016

It rinses off, but wouldn’t a flower with all its nooks and crannies and sticky tricombs hold it in?

By Nick on 28 October 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 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

By Nick on 28 October 2015

Massban it is called

By Nick on 28 October 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 bad…once in a while thing! 😉

By latewood_ILGM on 5 August 2017


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 🙂

By jb on 8 July 2016

Has anyone had broad mite problems, and if so, how do you get rid of the pesky little bastards?

By Discountdan on 3 October 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 awesome…

By Greenpheenrp on 28 August 2016

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

By Greenpheenrp on 28 August 2016

Anyone know any good cure for russet mites?

By Roy ILGM on 29 August 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.

By Jacko on 29 August 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 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.

By Jasna on 6 July 2017

Will turning the lights down for so long stress the plants out?

By Nic moore on 1 October 2016

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

By Reefer man on 14 December 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 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

By tbob on 13 February 2017

sounds like the 1989 bug oh bad hard to deal with

By Reefer man on 14 December 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

By Doug on 29 December 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” 🙁

By Roy ILGM on 29 December 2016

Sorry to hear Doug! I hope your next grow will bring you many delicious buds!

By latewood_ILGM on 13 March 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 of the DE.

Do not use Pool grade DE!

hope this helps 🙂


By tbob on 13 February 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

By John (Australia ) on 11 March 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

By latewood_ILGM on 13 March 2017


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 🙂


By Jasna on 6 July 2017

How long do the lights need to be out for applying the alcohol solution?

By latewood.ILGM on 11 July 2017


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.

By sicilianpie on 30 July 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 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…

By latewood.ILGM on 5 August 2017


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 🙂

By firstlegalcrop on 14 September 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.

By latewood_ILGM on 20 September 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 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. 🙂

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