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Pests and bugs on weed plants

Pests and Bugs on Weed Plants: Identify, Treat, Prevent!

Although cultivating homegrown buds is typically cheaper than buying them at a dispensary, it comes with the risk of pests. Bugs on weed can cripple your crop and hurt your plants. Early detection, accurate identification, and definitive prognosis are your allies in this battle.

This comprehensive pest guide covers the common critters that could derail your marijuana cultivation attempts.

We describe their physical traits, and damaging effects and share the best methods for their elimination. We also assess the beneficial bugs that may halt the spread of an infestation in its tracks.

Ready to learn about the creepy crawlies you could encounter? Let’s get started.

Identify pests on cannabis plants

When you grow marijuana, you may encounter various parasites and species. Precise identification is the essential first step and dictates how to get rid of bugs on weed plants. 


The appearance of ants around your cannabis crop is usually the result of an infestation of other organisms, like aphids or whiteflies. Those weed plant pests discharge honeydew that attracts this army of creatures.

example of an ant with a description
An ant – a common pest that one can find on the plants

Ants on cannabis aren’t initially a problem. They act as security, protecting their sweet, sticky honeydew source. When their numbers explode, they start building mounds and become a more serious issue.

They build nests in the growing medium, interfering with cannabis roots and their ability to take in water and nutrients. They don’t actively eat the foundations, but their relationship with other bugs on marijuana threatens the viability of your harvest.

ants on weed
Ants on cannabis and their damage. They are attracted to honeydew rather than the plants themselves


These oval-shaped, often wingless insects may display a spectrum of colors depending on the stage of their lifecycle and location. Some are black, while others have red, green, yellow, white, or gray hues.

an picture of an aphid with a description
Here is an aphid – a green, yellow or brown bug. Their color depend on the hemp they are inhabited. On cannabis, they are typically green

Aphids are among the most common cannabis pests and live in colonies of hundreds or even thousands. The females can reproduce without copulation and create new generations multiple times a day.

They hang out on the underside of leaves and use their sucking mouthparts to pierce leaves, stems, or buds to gorge on the juices. Once attached to the plant, they continuously excrete a liquid called honeydew. 

The sticky, sugary substance attracts mold that can turn plant leaves and stems black. Leaves can also turn yellow, and the plant may wilt. Honeydew also lures ants that you may spot around the base of the plants and protect aphids from predators. 

Separate an infested plant from your crop and spray it with neem oil or insecticidal soap. Remove heavily damaged leaves or buds. Spinosad is a natural solution from bacteria that can be toxic to insects. It’s also widely used to control many marijuana pests.

aphids on weed
Aphids on cannabis and their damage

Barnacle Scales

Barnacles, or scale insects, are a family of unusual pests that vary in appearance but act similarly. They may look like bugs, scales, warts, bumps, or growths. 

an example of a barnacle scale with a description
A barnacle scale – a rare cannabis pest

They don’t move once established and suck the life out of your plants. These pests belong to the Hemiptera family and have various patterns and colors. They affix themselves to cannabis plants, stems, or leaves and feed on the juice and nutrients.

Like aphids, they secrete honeydew that attracts ants and creates dark spots of sooty mold. In extreme cases, these weed bugs weaken the plant and stunt growth

Eliminate barnacles by using a small hand mister with insecticidal soap, neem oil, or spinosad solution. Natural pesticides made from essential oils can also eliminate the problem. Bug Blaster neutralizes virtually all pests.

barnacle scales on weed plants
Barnacle scales on weed plants and their damage. Like ants, they are attracted to honeydew produced by other insects

Broad mites

These little bugs often escape detection despite the use of a magnifying glass. The pot plant pests hide between leaves in the buds and lay their eggs out of sight. Broad mites may be translucent, yellow, or brown and possess four pairs of legs.

an example of a broad mite with a description
A picture of a broad mite – a common pest

An infestation can compromise new growth, which may twist, droop, deform, or blister. The mites inject a toxin while feeding, which causes brown buds and flower death in extreme cases.

Infestations are often improperly diagnosed as pH problems, overwatering, heat damage, or nutrient deficiencies. 

These marijuana plant bugs are challenging to clear and require long-term, repeat treatments. Predator Neoseiulus mites reduce numbers, but chemical miticides like Forbid, Avid, or IC3 kill them. Essential oils and insecticidal solutions also help.

Broad mites on weed
Broad mites on cannabis and their damage. These insects are killing the plants and are very hard to diagnose

Caterpillars, inchworms, and loopers

Caterpillars have multiple legs, while inchworms have six forelegs and two to three pairs of hind ones. Loopers have two each at the front and the rear. They all come in various colors and feed on the leaves, stems, buds, and stalks.

an example of caterpillars with a description
Canterpillars are beautiful and can be of various colors and shapes

These easily spotted weed parasites cause gaping holes, especially in the leaves, and are more prevalent outdoors. Good circulation within the plant minimizes the risk. Moths or butterflies usually lay their eggs in the tallest parts of the plant. Their feces also cause fungal or rotting issues.

Bt spray is a biological insecticide containing Bacillus thuringiensis. It stops caterpillars on weed from feeding, and they soon die. Pyrethrum is a natural plant pesticide, but recent trials indicate it may be harmful to humans. Picking caterpillars, inchworms, and loopers off by hand is best.

caterpillars on weed
Caterpillars on cannabis and their damage. Lots of the caterpillars varieties adore eating hemp


Crickets are generally outdoor pests identified by their rowdy chatter and telltale feeding marks. These marijuana insects cause small holes in leaves when they eat the plant matter.

an example of a cricket with description
A picture of a cricket – a rare cannabis pest

Most people know about the field varieties easily removed by hand, but mole crickets attack the roots and stems. They’re lethal to seedlings and can lure larger pests which cause further damage.

Plant netting can keep them away, while insecticidal soap solutions, neem oil, and Bt spray also do the trick.

crickets on weed plants
Crickets on cannabis and their damage

Fungus gnats

These tiny larvae grow in wet soil and emerge from your marijuana plant roots. Compost with wood chips is particularly prone to these cannabis plant bugs that may damage the roots and curb growth.

an example of fungus gnat with description
A picture of an adult fungus gnat

Adults are more irritating than threatening, but they can still spread disease. Signs of an infestation include small flies buzzing around the lower reaches or crawling in the soil. Overwatering is most often associated with outbreaks of fungus gnats.

Sticky fly tape traps work well to limit numbers, but proper watering practices are vital. Drying out the top inch of soil makes reproduction more complicated, and neem oil treatment also helps. These weed pests make your crop more vulnerable to fungal infections.

Fungus gnats on weed
Fungus gnats on cannabis and their damage. They are very tough to identify in their larvae phase as they are very small.


Crickets and grasshoppers (and locusts, which have wings) are liable to strip your cannabis of much of their vegetation if left unchecked. They happily munch on leaves and stalks, causing extensive damage that impacts photosynthesis and slows growth

an example of a grasshopper with description
A tiny grasshopper

The best way to combat these cannabis plant bugs is to catch them early, as the effects can be extensive. The size of grasshoppers means you should be able to remove the critters by hand. Neem oil, spinosad products, and insecticidal soaps also solve the problem. 

grasshoppers on weed
Grasshopppers on cannabis and their damage


There are around 20,000 kinds of leafhoppers with a broad range of colors. They live up to their name, hopping from one leaf to another. The fronds they attack may suffer brown or yellow spots. 

an example of a leafhopper with description
A leafhopper – a common cannabos pest

They have six legs and wings. You typically notice these bugs on weed in early spring. These minute insects become a menace in hot, dry weather when they need the moisture of leaf sap. They spread certain diseases and lay their eggs on or under the blades.

Insecticidal sprays and neem oil control outbreaks effectively but may affect the taste and safety of your product. Spinosad is natural and safer, while some growers employ beneficial predators.

leafhoppers on weed
Leafhoppers look nice but they damage cannabis plants.

Leaf miners

Leaf miners is an umbrella term that includes many species. The larvae burrow into the leaves and create squiggly brown or white tracks that simplify diagnosis. While the damage may cause some slowdown in growth, it’s mostly superficial.

an example of a leaf miner with description
A leaf miner with its larvae

Growers can eliminate the larvae by squeezing the leaves with their fingers or introducing parasitic wasps like Diglyphus isaea. Spraying general pesticide only works if done at the right time since the larval cannabis insects reside within the plant walls.

leaf miners on weed
Leaf miners on cannabis and their damage. Here you can see tiny traits left by the miners


These insects seek out the juicy sap of weed plants. They’re white, hairy bugs that look like woodlice and most often attack outdoor crops. Mealybugs secrete honeydew that attracts other parasites and causes mold, interfering with plant health.

an example of a mealy bug on weed
A mealy bug under a microscope

These cannabis plant pests can be tough to eradicate. The best option is to cut away the most infected parts. Alcohol-based sprays and soapy solutions keep numbers under control. Neem, cinnamon, or garlic oil provide respite but require repeated treatments daily.

mealybugs on weed
Mealy bugs on cannabis and their damage on plants. Mealy bugs produce honeydew that attract other insects on plants


These small, white-winged insects feed on the sap of cannabis flora. They leave a cotton-like secretion that growers may mistake for mold or white powdery mildew. The pests’ appearance varies depending on the lifecycle phase, but adults mimic a leaf.

an example of a planthopper with a description
A green plant hopper

These marijuana plant bugs aren’t overly serious in limited numbers, but a full-blown infestation results in sickly, yellow plants. The risk is most significant during dry conditions as the planthoppers seek moisture.

They’re well camouflaged and try to hide below the leaves when spotted. Spinosad, soapy sprays, and organic insecticides should halt an outbreak. Beneficial insects like ladybugs, lacewings, and predator wasps regulate numbers.

planthoppers on weed
Planthoppers on cannabis and their damage: small brown dots on leaves

Russet mites

These pests are minuscule, and you typically need a magnifier to spot individual bugs on cannabis plants. You may notice a yellow mass often confused for fungus, mold, pollen, heat damage, or a nutrient deficiency. The pale, four-legged mites live in crevices of the flora.

an example of a russet mite with a description
A russet mite – a common pest you can find on cannabis

Severe symptoms often occur towards the top of the plants, causing a drooping canopy. Leaf edges may curl, showing brown or yellow spots. Hemp russet mites live within the foliage, causing brown, brittle, and dead fronds. During flowering, they invade the buds, trashing yields. 

You may need to write off some plants in extreme cases. Otherwise, employ the usual soaps and insecticides. Keep in mind that these cannabis bugs are complicated to exterminate and require repeat applications for up to five weeks. 

They lay eggs within the plants, which makes them tricky to neutralize. Many regular miticides are ineffective. Don’t employ potent chemical pesticides like Avid or Forbid during flowering. Only use them as a last resort and alternate them to prevent resistance.

russet mites on weed
Russet mites on cannabis and their damage – small white dots

Spider mites

Spider mites are tiny, so you may need a magnifying glass to see their usual brown color and twin spots. They can also be yellow, white, or red. Females need to mate only once to reproduce for life, laying up to 100 eggs every five days.

an example of a spider mite with a description
A picture of a red spider mite

These troublesome cannabis pests leave small yellow, white, or orange spots that are often misdiagnosed. They pierce individual cells and suck the sap out of them. Signs of a severe infestation are bronze or yellow leaves and webs covering the foliage.

Sufficient air circulation and cool temperatures impair their ability to reproduce. The mites rapidly colonize a plant and are tough to shift, developing resistance to many countermeasures. Growers often use spinosad, insecticidal soaps, IC3, and neem oil in tandem.

spider mites on weed
A picture of spider mites on cannabis and their damage. The damage is very similar to russet mites. However, you can spots spiders and their webbings on cannabis plants

Stink bugs

These insects give off a foul-smelling odor and are harmless to humans, but your cannabis crops are another matter. Stink bugs are a pest to weed plants and feed on developing seeds, leaves, and buds, diminishing output.

an example of a stink bug with a description
A stink bug – a common cannabis pest

They invade grow rooms in cooler weather and hide amongst the debris, so a clean operation is vital. Cover outdoor plants with netting to avoid an epidemic. 

Don’t squish or spray them with insecticide, as you may reap a stinky reward. Dead bugs on pot plants attract other pests, too. Remove them carefully and eliminate any leaves with patches of white eggs. Take indoor plants outside and spray them with water, or use a vacuum cleaner.

stink bugs on cannabis
Stick bugs with their eggs on cannabis and their damage


More commonly found on indoor crops, these pests vary from translucent to dark. Adults have wings and long antennae. The females bore a hole in the leaf to lay their eggs. 

an example of thrips with a description
A thrip – a common cannabis pest

Thrips cause light-colored patches on marijuana leaves that impact photosynthesis, slow growth, and affect health, potency, and yield. These pot plant bugs strip chlorophyll from the fronds, which may become brittle and disintegrate.

It’s much easier to avoid these pests than to eliminate them, but soapy disinfectants, neem oil, and spinosad solutions help. Natural predatory mites like Orius and Amblyseius cucumeris reduce numbers.

thrips damage on cannabis
Thrips and their damage on cannabis

Whiteflies, white fly

These common marijuana pests are easy to spot but difficult to suppress. They look like tiny moths and lurk in clusters on the underside of foliage. They puncture leaves to get the sap and often cause yellow or white dots.

an example of a white fly with a description
A white fly – common cannabis pest

Whiteflies excrete sweet honeydew, which attracts ants and causes sooty mold. These white bugs feed on new growth, draining plants of nutrients. This action causes wilting and stunts growth. The marijuana bugs also weaken the immune system and spread disease.

Immediately address the problem if you notice a white fly outbreak. Sticky fly traps and natural predators like Encarsia formosa wasps help. 

The white-winged pests quickly develop a resistance to chemical insecticides, which work better when focused on the larvae. Organic pesticides like neem oil, spinosad, IC3, and insecticidal soaps require multiple applications.

white flies damage on weed plants
White flies damage on cannabis stems and leaves. These insects produce honeydew and attracts other cannabis pests

Slugs, snails

Most growers have a negative opinion of these slimy characters, but fewer than 50% of them are harmful to your crops. Even slugs or snails that cause damage play a vital role in recycling animal waste and cleaning up plant detritus. 

an example of slugs and snail with a description
Slugs and smails can be found on cannabis

Many are essential to the health of an ecosystem, devouring algae and other growths. They constitute a critical step in the food chain, providing sustenance for birds, toads, mice, and salamanders.

These gastropods belong to the family of soft, fleshy animals called mollusks. They’re related to clams, oysters, and squid. They can devastate crops, and most growers include them on their cannabis pests chart. They generally appear in spring which is the start of the growing season.

slugs and snails on weed
Slugs like to eat hemp and weed leaves

Identify your helpers: Beneficial bugs

beneficial insects
Here are your helpers that can help you get rid of most of cannabis pests without pesticides

Most pests have biological enemies, and introducing them into your growing environment can halt an outbreak. We evaluate what bugs are good for weed plants and examine some of the most effective predators below: 

Green lacewings

These multi-purpose predatory insects feed on cannabis pests like leafhoppers, aphids, thrips, spider mites, mealybugs, and other soft-bodied insects. Chrysoperla rufilabris are green, thin, flying insects that lay egg stalks on your weed.

When they hatch, the larvae immediately start devouring pests on cannabis plants. They ward off infestations and improve harvest health. If you buy lacewings online, they’re fragile and usually shipped in egg form, so they don’t fly off.

You can introduce them indoors and outside. Adult green lacewings don’t feed on pests but produce the next generation. They eat honeydew, pollen, and nectar but hang around your garden if there’s a supply of food for their offspring.

Planting wildflowers in your outdoor garden provides a source of nectar or pollen for the adults. It ensures these helpful bugs stay around to maintain the health of your marijuana flowers. 


Ladybugs are one of the best forms of pest control for cannabis. The pretty red and black critters won’t harm your crop and use their considerable appetite to eliminate pests. These predatory insects are particularly partial to pest larvae. 

Their bright coloration warns off potential attackers, indicating poison. They can secrete a bitter yellow substance that’s toxic to their enemies. 

Ladybugs are voracious and can eat 50 aphids per day. They count spider mites, whiteflies, mealybugs, cochineals, and other soft-bodied pests as food. Not all ladybug species can consume these bugs on marijuana plants, though. 

Flowering cannabis isn’t the most suitable host for ladybirds. At this time, only abundant prey can cause them to develop rapidly. Environmental conditions also determine how successful they are.


These tiny creatures come in 25,000 different forms, with 50% showing parasitic effects that harm crops, insects, and other animals. There are also benign nematodes that manufacturers can culture like bacteria, using them to inoculate soil and ward off several marijuana plant pests. 

These roundworms are available commercially and should remain refrigerated until needed. Mix them with warm water and sprinkle the solution on the soil. They multiply quickly and consume fungus gnats, spores, and larvae.

Steinernema feltiae is an example of a beneficial nematode. It attacks the larvae of the substrate fly, which hangs out at the base of cannabis plants in humid conditions. Nematodes also attack ants, flies, leafminers, moths, and other bugs.

Praying mantis

Stagmomantis are prolific hunters that provide cannabis pest control. They have a natural affinity for aphids, whiteflies, crickets, grasshoppers, mealybugs, caterpillars, and spider mites. 

These patient hunters wait for their prey to come to them. Like other beneficial predators, they move on if they eliminate all pests.

Don’t spray your herb with chemical insecticides. Take care when removing vegetation, as praying mantis egg cases may be attached. If you buy mantids, ensure they’re native to your area and not invasive. 

Predator mites

These pests come in three different forms:

  • Type 1 is a specific group that only feeds on spider mites.
  • Type 2 is an intermediate group.
  • Type 3 is a general group that eats a range of bugs on cannabis, including mites, thrips, and fungus gnats.

Phytoseiulus persimilis is an example of a Type 1 that can eliminate or regulate a spider mite outbreak. They control the population, allowing cannabis crops to recover and produce decent yields. 

Predator mites resort to ingesting pollen, nectar, and plant sap if they eliminate all prey.

Rove beetles

These red and black bugs target fungal gnats often found in the soil around the roots. The gnats appear in compost or soil mixes with wood components, especially when overwatered. They also consume thrips and root aphids.

Rove beetles (Dalotia coriaria) are soil-dwelling but adaptable, making themselves equally comfortable in coco coir or rockwool mediums. It makes them uniquely well-suited to marijuana pest control. 

Large animal pests

Larger mammals may also be attracted to your cannabis crops and can cause catastrophic overnight damage:

  • Dogs and cats love hanging out in the garden, but their feces encourage other pests and could introduce disease. Felines also like chewing on the leaves. Scents like garlic or cinnamon deter them, but the best bet is a solid fence.
  • Birds are outdoor weed pests that may steal your seeds or defecate on your crops. They have one benefit: they sometimes eat smaller insects that threaten your crop. Netting usually wards them off. Indoor germination keeps your seeds safe.
  • Rats and mice aren’t attracted to cannabis but love to chew on things. A clean garden without trash is unlikely to encourage these rodents. Cats, owls, and other predators regulate and deter these pests.
  • Moles burrow through the soil and leave your plants high and dry as they hunt for worms and grubs. A screen barrier around the roots protects your foundations. Extending your fence three feet underground prevents these marijuana pests from entering your weed garden.
  • Gophers and rabbits also use tunnels, but they devour the roots and leaves of your plants. Screening protects the roots while predator urine (coyote works well) around the base of the plant wards off herbivores.
  • Raccoons flip the soil to eat the insects, worms, and grubs below the surface. Skunks also use their sense of smell to dig holes and locate subterranean bugs. Both threaten your crops. Spray castor oil repellents on the surface to mask the aroma that drives these cannabis pests.
  • Tree squirrels dig holes to stash their food and can be a menace. Repellants and netting keep them away. Ground squirrels are more like gophers and rabbits and actively eat the roots. Screens and deep fences are effective deterrents.
  • Large animal pests like deer only eat cannabis when there’s nothing else available. They’re potentially ruinous, especially if there’s more than one. Cloven hoof tracks or droppings are clues to the culprits. Fencing is your only recourse.

Say goodbye to bugs on weed

Now you have all the information you need to face common bug infestations confidently. Avoiding these cannabis pests altogether is first prize. Knowing your enemies and how to minimize their impact improves the potential of your harvest.

Precise analysis and early identification are crucial to controlling outbreaks, but some bugs are trickier to pin down than others. Fortunately, most fixes cover multiple species and simplify efforts. Keeping a clean growing area is a start, but organic insecticides also help.

Consider introducing beneficial predators to address an infestation. These natural enemies regulate marijuana bugs and could rescue your harvest. When all else fails, use chemical cures but never during the flowering phase.

Buy premium cannabis seeds from our online seed bank and put your newly-acquired knowledge to the test.

AUTHORED BY: Douglas Kester Mr. Kester came to i49 with a wealth of experience. He’s worked in the cannabis industry for more than ten years. As a growing expert at i49, Douglas finds it hard to choose a favorite strain. Instead, he regards each one as unique and full of potential. Douglas finds it rewarding to experiment with specific cultivars and cross-breed to discover a new one. He strongly believes in sharing the benefits of marijuana with as many people as possible to avoid any misconceptions about the herb. Mr. Kester creatively produces information based on what he’s learned and his experience obtained by implementing what he knows. i49 is proud to have Douglas as part of the team.

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