Cannabis Pests & Solutions

Cannabis is a huge hit, & not just among people.

Deer, birds, moles, squirrels, & raccoons are just a few animal fans that cause issues for outdoor growing areas while smaller admirers present problems for both outdoor & indoor growing environments.

One of the main benefits of growing indoors is the prevention of insects & infestations. However, if growers don't keep the environment clean &/or aren't cautious about what they're tracking in, these tiny admirers can wreak havoc & destroy an entire harvest.

The first step to avoiding insect infestation, as well as, fungus, mold, mildew, etc., is to ensure your grow room is kept extremely clean & that proper grow room air filtration is implemented to control & remove contaminants.

Find out how to identify insect pests & the best ways to prevent them below (detailed prevention instructions can be found at the bottom of this article).

Cannabis Cultivation Facility

Aphids - One of the most common cannabis pests

Identify Solutions
Colors range between grey, white, green, yellow, black, brown, or red based on their stage of life & where you're located. If a plant is infested move it to an outside area where you can spray it to cut down the population.
They are oval-shaped & may or may not have wings. Remove leaves & buds that are heavily infected.
They will feast on any part of a plant by biting into the leaf, stem, or bud to feed on the juices inside. Insecticidal soaps
They generally live in colonies of tens or hundreds & hang out on the undersides of stems & leaves. Neem oil
Once attached, an aphid becomes fixed & is easy to spot. Spinosad
Females do not require copulating to reproduce & will produce offspring between 3 to 100 times a day. Essentria IC3
Aphids secrete large volumes of sugary liquid water known as honeydew. Honeydew drops attract sooty mold that can grow on honeydew deposits found on leaves & branches turning them black.
If you notice ants around the base of your plant, this is also a sign of an aphid infestation as the ants are attracted to the sweet honeydew & protect aphids from predators.


Identify Solutions
Barnacles are scale insects & can appear in different colors & patterns. Use a small one-h& pressure sprayer to spray off the bugs.
Scale insects may vary in appearance but act the same. Insecticidal soaps
They can seem like growths on a plant or look like bugs. Neem oil
They hang out on stems & under leaves. Spinosad
Once they're established barnacles become stationary & suck the life out of the stem & leaves of plants. Essentria IC3
If infestations get too bad, your plant will start to weaken. Similar to aphids, barnacles also release honeydew.
Broad Mites

Broad Mites

Identify Solutions
Broad mites are very small & difficult to see even under a microscope. Neem oil
When your plant is infested with broad mites or russet mites new growth may come in twisted, blistered, & appear wet or plastic-like. Essentria IC3
If your plant is in the flowering stage, buds may turn brown & die. Insecticidal soaps
Broad mites normally hang out inside the crevices of leaves inside buds & they lay eggs inside of the plant. Mighty wash
Infestations are commonly diagnosed as overwatering, heat damage, or a nutrient deficiency. Avid
Prevention is different for broad mites since they are one of the toughest to get rid of. Forbid
When dealing with broad mites, it's recommended that you treat your plants for at least a few weeks at several times a week or even daily. Diatomaceous Earth
Repeat treatments for five more weeks after the mites are gone. Since they lay eggs inside of the plant they can come back if not completely destroyed. Heat

Caterpillars, Inchworms, & Loopers

Identify Solutions
Caterpillars have a lot of legs & come in a variety of colors. BT Spray
Loopers have two sets of feet, one at that back & one at the front. They arch their back to pull the rear feet forward. Spinosad
Inchworms have three pairs of front legs & either two or three pairs of rear legs. These worms can be found in any color & are any size about half an inch.
All three will eat through leaves, buds, stalks, & the main stem.
They defecate often with fungus & rot quickly follows.
They are not as common for indoor grow rooms & if proper air circulation is in place they should not be an issue.
If you notice holes in your leaves & think that these worms are in your plants, spray pyrethrum & shake your plant to make them fall out.
A caterpillar on a leaf.
Fungus Gnats

Fungus Gnats

Identify Solutions
Fungus gnat larvae are hard to see with the human eye & have transparent bodies & black heads. These gnats are common for plants that are watered too often.
They enjoy dark & moist environments & can be found at the base of your plant. Allowing the top inch of soil to dry out before watering can make them go away on their own.
Adults are grey to black in color & are very small with long legs. Blow air over the soil to dry it out making it harder for them to fly around & reproduce.
The females lay around 200 eggs per week within the first few inches of moist soil & larva can be typically be found in water runoff. Treat the top layer of soil with Neem oil.
Adult fungus gnats will generally be found swarming around the lower portion & at the base of your plant along with the larva. Apply Diatomaceous Earth to the top of the soil & around edges.
Once infested in the root system, these insects damage larger roots resulting in weak plants, slow growth, & fading foliage. Yellow sticky traps placed on the floor near plants & hanging near the top will help discourage their attack indoors.
Fungus gnats stick to the sticky flowering green & are almost impossible to remove. If you have a bad infestation, it may take weeks of good watering practices before they're gone.
The damage from these pests makes cannabis plants very vulnerable to various types of fungus.

Leaf Miners

Identify Solutions
Leaf miners are the larva of any bugs that live inside leaves & tunnel through them to eat. Environmental control indoors & in greenhouses will prevent bugs from laying eggs in your plant.
They are normally around 1/8" thick when hatching. Remove affected leaves if you can, if you don't want to remove the leave, crush the larva by pressing your fingers together where the trail is visible.
It is uncommon to notice leaf miners before noticing the damage they leave. Spinosad
These pests live inside the tissue of leaves, eating the best parts, & leaving a trail of damage behind. Neem oil
If you find a leaf that a miner is burrowing through it may be visible. BT spray (if evidence of caterpillars or loopers is present)
Leaf Miners
Spider Mites

Spider Mites - Common pests that are difficult to get rid of

Identify Solutions
Spider mites live underneath the leaves of a plant & are so tiny they look spots to the naked eye. Reduce their population by controlling the heat, this makes it harder for them to reproduce in cooler temperatures.
The leaves of your plant will be covered in yellow, orange, or white speckles which may be misdiagnosed as a nutrient deficiency. Blowing constant air over the plants combined with the cooler temps creates a cool breezy space & makes it harder for reproduction.
When spider mites attack a certain spot you will see a lot of specks near each other & the leaves may start to appear yellow or bronzed. Taking plants outside & spraying them off if possible to reduce population before starting the main treatments.
When the infestation grows you'll notice webbing that may cover foliage, flowers, & even entire buds. Spiders may be brought in by a new plant or a clone. It's important to look for new bugs or tiny spots on leaves using a microscope or magnifying glass.
Their sharp mouths pierce individual plant cells & suck out the liquid that keeps your plant alive. Keeping new plants in quarantine for at least a week & checking daily for bugs is great practice to implement.
Spider mites are visible under a strong magnifying glass & are commonly brown with two spots but can be yellow & white or red. Mighty wash.
Female spider mites become fertilized for their entire life cycle once they mate & lay on average around 100 eggs every five days (around 1 million a month). Spinosad
75% of all spider mite eggs become female. Essentria IC3
Spider mites will quickly take over a plant & can easily develop resistance to almost any method used against them. Insecticidal soaps
It's recommended to use various methods to remove them. Neem oil
  Diatomaceous Earth

Thrips - Common insect pest for indoor growers

Identify Solutions
Because it is difficult for thrip to reproduce in large quantities outside they make their way into indoor growing spaces. Insecticidal soaps
They are very very small & can almost be any color. Neem oil
They may appear dark, yellow, golden, or translucent. Spinosad
Based on stage of life they may or may not have wings.
It's hard to see a thrip on its own but they generally move in herds together.
Thrip leave behind shiny silver or bronze spots where the leaves were bitten. Damage has been described as dried spit.
They strip leaves of chlorophyll & the leaves turn brittle & dark & then crumble.
Female thrip creates a hole in the plant matter where she leaves her eggs.
Thrip flourishes & reproduces inside of buds.
Shaking branches will make thrip fly &/or jump to other places to live.


Identify Solutions
Similar to spider mites, whiteflies hang out & steal nutrients from underneath cannabis leaves. Insecticidal soaps
They are easy to spot but can become hard to get rid of if ignored. Neem oil
Their eggs stick to the leaves like glue & cannot be wiped off. Spinosad
They prefer weak plants & attack them from the top down. Essentria IC3
Leaf damage from whiteflies is similar to spider mites. The longer damage continues the more strength & energy.

Solution Methods

Move your plants outside & use a power sprayer to physically spray off all the bugs. You should also remove heavily infected parts of the plant & for 2x effectiveness use an insecticide while spraying to treat future attacks.


Avid is harsh & expensive but works if nothing else is getting the job done. This insecticide infiltrates the inside of the plant tissue & should not be used during the flowering stage.

Don't use this product more than once or twice in a row as the mites can become resistant. If you decide to use systemic insecticides, switch back & forth between Acid & a product like Forbid.

BT (Bacillus Thuringiensis) Spray

A biological insecticide that kills larva & prevents pests from being able to eat. You'll want to apply this spray as soon as you notice any signs of an insect infestation.

Diatomaceous Earth

A powder-like substance that is sprinkled on top of the soil & anywhere else in the room. Diatomaceous Earth is harmless to animals & plants but is exceptionally sharp at a microscopic level.

It will tear & dehydrate mites on physical contact but it will not get rid of an infestation. It will, however, prevent & slow it down when used effectively.

It will kill adults & larvae fungus gnats that touch it.

Essentria IC3 Insecticide

Also known as bed bug killer, Essentria IC3 is a mix of various horticultural oils that are organic & safe for humans. This method only stays effective on the plant for about 8 hours so you'll need to apply it daily or combine with another option.


Like Avid, Forbid is made with strong chemicals, is expensive, & also infiltrates the inside of plant tissue.

Don't use this product more than once or twice in a row as the mites can become resistant. If you decide to use systemic insecticides, switch back & forth between Forbid & a product like Avid.


Heat runs out broad & russet mites. Growers may try & get rid of them on small plants by submerging the plants in hot water for 10-20 minutes at 105°F or by heating up to grow room to 115°F for 60 minutes.

Please keep in mind that this can be dangerous to the health of your plants.

Insecticidal Soaps

Insecticidal soaps weaken the outer shell of aphids, barnacles, mites, thrips, & whiteflies & are safe to use on plants. Additional applications may be required.

Even though this is considered safe it's best practice to avoid getting any on buds.

Mighty Wash

Can be used to drench leaves 15 minutes before lights go out ensuring that the foliage under the leaves & top of your soil is covered. Use a mister to spray & a fan to help dry.

Neem Oil

An all-natural remedy that is effective against many types of bugs & mold. However, it leaves an unpleasant smell & taste so don't let it near your buds.


Spinosad products are organic & completely harmless to pets, children, & plants.

Spinosad can be used directly to kill aphids & leaf miners & can be sprayed liberally.

It can kill barnacles but their shell makes them resistant, so it’s important to cover all of the vegetation.

Not as effective as BT spray for caterpillars, inch worms, & loopers, but can kill them if sprayed directly on contact.

Spinosad can be used to kill spider mites, thrips, & whiteflies on contact & can be used when watering plants to kill spider mites from the roots.

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