Cannabis: Bugs and Insects

Bug on cannabis plant
September 26, 2020

When it comes to cannabis plant pests, insects are not all you need to worry about. However, they can also be quite frightening, considering how much damage they can do. Once they attack your marijuana plants, the destruction can be catastrophic if you don’t quickly recognize the culprit and eliminate them. It does not matter if you are a beginner or an expert. Even veterans encounter them every now and then.

How do you keep your plants safe?

Be informed and know what to do for prevention. If you have an infestation of bugs that eat marijuana plants, specifically your plants, then know how to identify which species and take necessary measures to get rid of them.

Why Do Insects Attack Marijuana Plants?

It is not uncommon to find bugs on pot plants in your grow. These pests can be destructive because not only do they drain precious nutrients. They also cause physical and, sometimes, irreversible damages. Consequently, the plants would not reach their full potential – if they survive. As a result, you end up with a poor harvest – buds’ overall quality and yields leave something to be desired. If you do not control the infestation, the worst thing that can happen is that your plants die.

Unfortunately, there are far too many species of insects that could cause harm in your garden. Even if you are growing marijuana inside a sealed grow tent, an insect might find its way inside to start a colony. Knowing what bugs to watch out for, in this case, raises your awareness and better prepares you for preventing or remedying a crisis.

Bugs that Eat Marijuana

Here are the most common cannabis pests that you need to keep an eye on and the tell-tale signs of an infestation.


Ants are unlike other pests in that they do not feed on your plants or cause damage directly. They are more likely to be cannabis pests in soil as they can make life tougher for the root systems by digging tunnels and forming mounds on the soil. This, in turn, might interfere with nutrient and water intake. One thing good about ants is that they also act as an early warning device. Usually, their unusual presence is an indicator of other problems, such as whiteflies or aphids.


These are tiny, nearly translucent insects that are usually found on the leaf undersides. Due to their minuscule size, spotting them can be challenging. Mainly, they bore through the leaves and suck the sap. Even if only there are a few of them, they can reproduce quickly. A large population not only damages the leaves but also deprives the plants of nutrients.


Although they appear benign, these critters can wreak havoc on the cannabis plants. They are ravenous and love chomping on the leaves. Certain types of caterpillars could even burrow into the plant interior, consuming them from the inside out. Due diligence in caring for the plants means you have to watch out for insects. The last thing you want to happen is not noticing your precious ladies incurring substantial damage.


These moth larvae are perplexing, some of the most common cannabis pests in soil. You cannot catch them attacking the plants because they only come out during the dark period. Once the lights are turned on (or during the daytime), they hide under litter or soil. Seedlings and young plants are most vulnerable. A sign that you should watch out for is the top growth appearing as if they were cut down.

Crickets and Grasshoppers

These two insects are not only loud and virtually everywhere. They also have voracious appetites and love nibbling on marijuana plants. Unfortunately, they are sneaky and typically strike under cover of darkness. In most cases, you would only detect them once they have already fed on the plants. Mounds of dirt and brown patches on the plants are two red flags alerting you to their presence.

Fungus Gnats

These are small insects that could harm the root systems and the stems. They are most dangerous during the larval phase, chewing on the roots and possibly even spreading plant diseases. Fungus gnat eggs – usually found under the soil – appear translucent with a black, shiny head. If you suspect an infestation, place a sticky pad near the plant base to capture the elusive eggs.

Leaf Miners

As the name suggests, these insects like mining through the leaves, causing damage and depleting valuable nutrients. Leaf miners usually leave a brown or white trail on the leaf surface. The adult ones resemble regular house-flies, whereas the larvae look like light-colored maggots. They hatch under the leaves before eventually digging through the interior.


Only female mealybugs – which are small, soft-bodied, and wingless – are visible on plants. They could weaken cannabis plants by feeding on their juices, causing the leafage to turn yellow, wilt, and drop off. A common sign of mealybugs is having fluffy white deposits on the plant. The presence of ants is another indicator.

Spider Mites

These are small, sucking pests that are related to spiders and ticks. Spider mites feast on cannabis plants, robbing them of precious nutrients. They are also known to reproduce and mature quickly, which means that they could take over the garden and ravage the plants with alarming speed. To identify spider mites, look for webbings on the plant. Position a magnifying glass over the leaf surface or underside to see if tiny spiders are moving across it.


Appearing as little white bugs on pot plants, these soft-bodied, winged insects are closely related to aphids and mealybugs. Typically found on the leaf undersides, whiteflies suck on the plants, sapping valuable resources. They tend to feed on newer growths, leading to yellowing, stunted growth, and reduced yields. Even worse, they could also spread plant diseases.

How Do You Prevent Insects from Damaging the Plants?

As soon as you notice insects around the plants, your first instinct might be to buy an insecticide (pesticide). Use organic or natural solutions. The problem with many commercial products is that they are laden with chemicals that could be toxic to both humans and the environment.

You could, for example, consume marijuana buds tainted with the toxins. Or, your food and water source may contain pesticide residues. And in humans, exposure to such chemicals has been associated with dangerous health risks.

The toxic chemicals could also wreak havoc on the environment once released as runoff. Not only does it harm the soil microbial life but also other wildlife and non-target organisms. It could even contaminate the very air we breathe.

Fortunately, there are organic options available. Here are 5 methods you should try to keep the growing area pest-free.

1. Natural Foliar Sprays

Once you see pests loitering on your cannabis plants, it is important to act immediately. Every wasted moment means more damage inflicted on the plants.

If you want a fast-acting remedy, you can’t go wrong with a foliar spray. Even better, you can easily make it at home using accessible materials. Alternatively, you can also buy ready-to-use ones. Just make sure that it is devoid of toxic chemicals.

Several all-natural blends exist, varying on the active ingredient used. Popular options include vegetable oil, garlic, chili, and neem oil. These are mixed with the appropriate ratios of mild liquid soap and water, then stored in a spray bottle.

To use, mist the concoction on the cannabis plants, ensuring that they are well-coated. Focus on the leaf undersides and the affected areas. Do not over-apply, though. You don’t want the plants to be dripping with the solution – that could do more harm than good.

Make sure to spray early in the morning or late afternoon. That is because the natural ingredients may degrade faster with light exposure. And use it only during the vegetative stage. It could affect trichome production when sprayed on blooming marijuana plants, compromising the potency, aroma, flavor, and overall quality of the buds.

2. Protective Barrier

Many of the pests infesting cannabis plants are creepy-crawlies. If you are dealing with one, consider forming a protective barrier around the garden. All you need to do is sprinkle generous amounts of diatomaceous earth – a whitish powder made from the fossil of tiny, aquatic animals – on the ground.

This naturally occurring material destroys pests upon contact – but not instantly. It could take hours. Mainly, it works by dehydrating the insect and by absorbing the oils and fats from the exoskeleton. Due to being sharp-edged, it may also injure the pest, speeding up the killing process. As a bonus, it also serves as a preventive measure, deterring the insects from getting close.

Keep in mind that diatomaceous earth has to be dry and undisturbed to remain an effective protective measure. When it rains, for example, you have to reapply it. Also, since it is abrasive, wear protective equipment during the application. Otherwise, it could irritate the skin, eyes, and airways.

3. Fly Strips

This fly-killing device is a sheet of paper coated with a sweet-smelling and incredibly sticky substance. Primarily, it traps flying insects that land upon it. After a while, the airborne invaders – such as fungus gnats and whiteflies – will die from exhaustion, starvation, or injuries.

To use, simply hang the strip from the ceiling. Opt for strategic spots like window panes and entrances. Do note that it loses its efficacy over time upon drying out or getting dusty. So, if you are growing outdoors, you may have to replace it more often.

4. Natural Predators

This approach capitalizes on one of the hallmarks of the wild outdoors – predation. By introducing predatory insects into the garden, you are letting them do the grunt work of eliminating the pests.

Ladybugs, for example, can eat about 50 aphids a day. Mealybugs, mites, whiteflies, and other tiny, soft-bellied insects are not spared from its killing prowess. Praying mantis is yet another voracious feeder, killing most pests, mites, and eggs. Finally, if you are dealing with caterpillars, consider parasitic wasps.

These natural predators are widely available online or local garden supply stores. Do read up on how to properly introduce them to the growing area, though. Ladybugs, for instance, are best released at twilight hours. It also helps to do so near the infested plant so they could immediately find food. As for the water source, ready shallow dishes filled with water and a layer of pebbles.

5. Companion Planting

Companion planting is the practice of growing different plant species in the same area to reap some kind of benefit. Some plants, for instance, attract predatory insects by providing them with food and shelter. Others confuse or ward off pesky critters by releasing chemicals. Incidentally, some plants could do both. If done correctly, you could lower the pest population while preventing the pests from venturing close.

Here are some companion plants you can raise alongside your marijuana crops.


This herb from the celery family is intensely aromatic, attracting natural predators like honeybees, hoverflies, and ichneumon wasps. On top of that, it could also fend off aphids, cabbage loopers, spider mites, and squash bugs.


Due to having high amounts of sulfur, garlic has potent insecticidal and anti-fungal properties. The overwhelming odor also disorients and drives away a wide range of pests, including ants, aphids, fungus gnats, and spider mites.


Known for its vibrant flowers, marigold could ward off damaging insects like beetles, nematodes, and whiteflies. This is mainly due to its having an abundance of limonene – a terpene with natural insecticidal action and other chemicals toxic to pests. Additionally, it could lure in ladybugs and other beneficial bugs.


The distinct menthol fragrance of peppermint is not only for culinary, household, and medicinal applications. It could also chase away ants, aphids, beetles, and flees while ensnaring predatory insects like ladybugs and hoverflies. Take note that it tends to have invasive growth patterns, so make sure to position it strategically.


This flowering plant gives off a pleasantly sweet, spicy aroma that could draw in aphid lions, hoverflies, ladybugs, and wasps. These natural predators, in turn, feed on spider mites and other harmful critters.

No More Insects Killing Your Marijuana Plants

Pests are the bane of every grower’s existence. Sadly, there is no shortage of stories where these pesky insects have ravaged the garden beyond belief. But this does not have to be your fate. If you know what to watch out for and how to address and avoid them, keep your marijuana plants safe and sound. And, you do not even have to resort to toxic chemicals to do so.

More importantly, make sure to keep the plants healthy and well-nourished. If they are in peak condition, they are less likely to attract these troublesome bugs in the first place. In the like manner, ensure that the growing area is clean and inhospitable to pests. With vigilance and quick action, you could successfully harvest the purest and most potent ganja of your dreams.