Aphids on Cannabis? How to Spot, Stop, and Prevent These Pesky Pests for Good!

We all have that one friend who invites himself and his friends over, eats all your food, and leaves a mess behind. Aphids are no different. Only, they are NOT your friends. If you've grown cannabis before, you're probably already aware of the destruction it can leave behind, but just in case you've been lucky to never encounter it, just know that this little monster can reproduce quicker than you can eliminate it.

These tiny green, yellow, or black bugs may look harmless at first until you see how your plant suffers. A single aphid can produce dozens of babies per week, meaning a small infestation can turn into a full-blown disaster before you even realize what's happening.

Both indoor and outdoor cannabis growers are at risk of infestations of aphids. Outdoor plants are more exposed to migrating aphids but indoor growers are also at risk of infestations after bringing in contaminated plants or clones. So, you need to learn how to recognize and spot aphids, prevent future outbreaks, and get rid of them. 

If you're tired of these uninvited freeloaders sucking the life out of your plants, don't worry — you're not alone, and you're definitely not helpless. In this guide, we'll break down exactly what aphids are, how to identify them, and, most importantly, how to get rid of them using natural, organic, and chemical solutions. Whether you're growing indoors, outdoors, or somewhere in between, we've got you covered.

At the end of this article, you'll hopefully know how to spot aphids before they take over your plants, natural and chemical solutions for eliminating them, and long-term prevention strategies to keep them from coming back. 

What Are Aphids?

Aphids are small, soft-bodied insects that are one of the most common cannabis pests. They are under the insect family Aphididae and may be found in almost every growing environment from outdoor gardens to indoor grow rooms. These insects will thrive in warm conditions and reproduce quickly, making them serious threats to cannabis growers.

Typically, aphids harm plants by sucking the sap from them and depriving them of nutrients. Apart from that, they produce honeydew — a sticky substance that invites mold and also other pests. Now you know why we were talking about that annoying friend inviting his own friends, eh?

But, how do you identify them? Well, as mentioned before, they can be green, yellow, black, brown, pink, and anything in between. The color of these insects largely depends on their species and hosts. Typically, they are about 1 to 3 mm long and have a pear-shaped body with long antennae and legs.

Some aphids develop wings, while others remain wingless. Aphids that have wings generally appear when there are so many that they need to get to other plants. Aphids easily travel from one cannabis plant to another to feed. As a result, your problem may not be isolated to just one or two plants.

Also, these insects usually clump together in large groups on the underside of cannabis leaves, stems, and new growth to suck the plant sap. At the beginning of an aphid infestation, you might not even notice them, but as more of the pests end up on your cannabis, the visual changes become more apparent.

Here's how to recognize aphids on cannabis plants. 

• Clusters of little insects on stalks, leaves, or near bud sites.
• Sticky residue (honeydew) on leaves and stems.
• Black sooty mold growing on honeydew.
• Distorted or curled leaves.
• Yellowing or browning foliage.
• Wilting or stunted plant growth.

It is crucial to identify aphids early so that they do not severely harm your cannabis plants.

Life Cycle of Aphids

Aphids reproduce quickly and have a highly specialized lifecycle. Because of this, they can become a nuisance in no time at all. Their life-cycle consists of the following stages.

1. Egg stage: Aphids will lay their eggs in debris surrounding the plant or soil during the cold periods. When the temperatures increase, the eggs will hatch and aphids will emerge. But, when it's warm, some aphid species can even bypass the egg stage entirely.
2. Nymph Stage: Young aphids (nymphs) begin feeding plant sap soon after hatching. They molt several times before adulthood and grow in size with each molt.
3. Adult stage: The adult female aphid does not need to mate in order to reproduce like most insects. They can also give birth to live nymphs without mating (this is called parthenogenesis) and populations can expand fast. As the aphids become too many, some of them develop wings to fly down and infest other plants.

Aphids can complete their entire life cycle in around one week under ideal conditions, meaning a population explosion can occur in a few days. A single female could give birth to 80 offspring in a week which is one of the fastest multiplication rates of any pests.

Why Are Aphids a Problem for Cannabis?

Aphids are a serious threat to cannabis for many reasons:

1. Sap-Sucking Behavior Weakens Plants

Aphids suck the sap out of cannabis stems using their sharp mouths. As a result, plants struggle to absorb nutrients from the soil and can fall prey to various pathogens and even mold. There will be a host of problems including:

• Nutrient Deficiencies: Plants use the sap to transmit nutrients that are indispensable for them. When aphids rob them of these nutrients, they develop yellowing leaves, weak stems, and poor growth. When aphids ingest the plant sap, it damages the plant tissue. As a result, the plant wilts, the leaves curl, and the stems become brittle. 
• Weakened Photosynthesis: Because of the damage done to leaves, they can't absorb sunlight as efficiently as before, thereby reducing the plant's growth and weakening its buds.

Think of it this way — imagine you're trying to grow big and strong, but every time you eat a meal, someone comes along and sucks half of it away with a straw. This is what happens when your plants are invaded by aphids. They starve your plants while selfishly feasting on their nutrients.

The more aphids there are, the worse the damage becomes. If an infestation is not treated in time, your plants could be stunted or deformed and you can bid goodbye to high-quality buds. 

2. Honeydew and Mold Growth

Aphids not only suck out plant juices, but they also produce a nasty, sticky substance known as honeydew. It coats the leaves and stems of the plant, causing big problems. How?

Well, the sugary waste that the aphids excrete on the plants attracts ants. Ants like honeydew more than you probably love candy. They will protect the aphids from predators to ensure the stock lasts as long as possible. The problem gets worse as ants actually grow aphids like little livestock.

Honeydew attracts the growth of sooty mold, a black fungal disease that coats leaves and prevents the plant from getting sunlight. And, when sunlight is reduced, it impacts photosynthesis, thereby weakening the plant and lowering the yields.

If the honeydew and mold build up way too much, they can move to other plants, making the issue become bigger than it needs to be. If sooty mold covers your plants over time, it can choke them out and make it virtually impossible for them to produce strong, resinous buds.

3. Spread Diseases

Aphids are not just annoying but are also carriers of deadly plant viruses. When they travel from one plant to another, they can spread incurable diseases that permanently damage cannabis. Let's take a look at some of the diseases they can spread:

• Viral Disease (Leaf Curl): Affects the plant and disfigures the leaves that curl downward and start cupping.
• Cannabis Mosaic Virus: Creates mosaic-like discoloration on leaves and weakens plant health.
• Bud Rot: Causes grey mold and other fungal infections. Aphid infestation weakens your cannabis plants, increasing susceptibility to these fungal infections.

Unlike aphid damage, viral infections cannot be reversed. If a plant ever gets infected, there's no fixing the problem. The plants need to be removed and thrown away.

In short, think of aphids as dirty needles at a doctor's office. When they prick a sick plant, and then go to a healthy one, they cause diseases, making them one of the most dangerous cannabis pests — they could infect your entire grow in just a few days.

4. Reduced Bud Quality and Yield Loss

Cannabis grower focuses on producing big and resinous buds having THC, CBD, and other cannabinoids after months of grooming. Aphids prefer young cannabis buds that have no defense.

In the vegetative stage, the plant will grow solely as it cannot conduct photosynthesis properly. The stems weaken, making the plants more likely to break under their weight. The slow development of their roots means that plants are less likely to absorb water and nutrients.

If the aphid infestation is bad enough, it can ruin a cannabis plant's ability to make quality buds entirely. Therefore, all the time and effort spent on this crop were all for naught.

Apart from this, here are a few problems you can face:

• Small Buds – Plants spend energy fighting aphids instead of producing large, dense flowers.
• Contaminated Buds – Honeydew buildup can lead to moldy buds, making them unsmokable and unsellable.
• Low Cannabinoids – Stressed plants produce fewer cannabinoids, reducing their potency.

Remember — don't wait until it's too late. Aphids are one of the most destructive cannabis pests; they don't hurt your harvest by gnawing on just a few leaves. Instead, they spread diseases, weaken the plant, and create havoc. If you really want to harvest big buds, you should make sure you prevent them in the first place. This is because even a few aphids can hurt the plants, especially autoflowering ones that don't have a lot of time to recover. 

Signs of Aphid Infestation on Cannabis Plants

At first, aphids are so tiny and small that they go unnoticed. But, as they start damaging the plants, you will notice them. If you can determine the infestation early, your plants might just make it. 

Here are the key signs of an aphid problem on cannabis plants:

1. Visual Indicators

The first and most obvious sign of an aphid infestation is the presence of insects. Aphids usually gather in groups on the undersides of leaves, new growth and young shoots, and bud sites and stems.

Aphids, despite their varied colors, are hard to see. The good news (which is actually really bad news) is that they form colonies that cover stems and leaves, making it obvious to you. At this point, it might just be too late to save the plant, but you can still try. 

Other visual indicators of aphid damage include:

• Aphids feed on sap from leaves which deform them. They look distorted and may start curling. 
• When aphids suck up the sap from leaves, a nutrient deficiency develops, so the leaves become yellow, most frequently in patches.
• The plants droop since they have less moisture.
• If these pests start feeding on younger plants, there will be visible stunted growth, causing them to become smaller and weaker.
• The appearance of winged aphids is another important warning sign. If you notice flying aphids around your cannabis plants, it means their population is so big that they are looking for new plants to host them.

2. Honeydew and Sooty Mold

Now, as you know already, aphids secrete honeydew. Although the honeydew itself does not directly harm plants, it leads to secondary problems, including mold growth and increased pest activity.

To identify honeydew, look out for these signs:

• Leaves and stems feel sticky to the touch.
• A shiny, wet-looking film appears on plant surfaces.
• Nearby surfaces, such as grow room floors, may become sticky.

The biggest issue with honeydew is that it attracts sooty mold. Sooty mold is a dark, black fungal growth that thrives on honeydew. This mold can quickly spread, covering leaves and reducing the plant's ability to photosynthesize.

As the light gets blocked, the plant's ability to produce energy decreases and weakens its overall growth. In addition, it can spread to other buds, ruining the quality of the final harvest.

If you notice sticky honeydew or black mold appearing on your plants, it is a strong indicator of an aphid infestation.

3. Ant Activity

If you notice a rise in ants around your cannabis plants, it is likely you have aphids. Ants are drawn to the honeydew that aphids produce. But ants don't only eat honeydew — they protect aphids against predators like ladybugs and lacewings.

Therefore, if you see them crawling up stems and leaves, your plants probably have aphids. Sometimes, ants even “tend” aphids, taking them to new places on the plant to help produce more honeydew, so you may see ant trails leading to and from your cannabis plants. It can be a warning sign of aphids if you see a sudden increase in ant activity around your grow space. 

How to Prevent Aphid Infestations?

Prevention is the best defense against aphids as they reproduce quickly. If they get out of control, they can cause significant damage to your cannabis plants. Therefore, taking steps to prevent aphids will save you time and money. Getting aphids away from cannabis can keep the plant healthy and yields high and you'll be able to enjoy the rewards later. 

Here are the best ways cannabis growers can prevent aphids from infesting their plants:

1. Companion Planting

Planting certain types of plants close to your cannabis can keep aphids away or attract their predators. You can also use beneficial insects to reduce aphid populations as it's one of the best ways to control aphids on your cannabis plants.

Best Companion Plants for Aphid Control

• Marigolds – Emit a strong scent that deters aphids.
• Chives and garlic contain sulfur compounds that can deter a range of pests.
• Basil – The aromatic oils keep aphids away from cannabis.
• Mint keeps pests away but spreads aggressively so you may need to use it or weed it often. Make mint tea frequently and you won't have to discard anything!
• Dill and fennel attract ladybugs and lacewings, which eat aphids.
• Yarrow is a much-loved insect-attracting plant that itself can repel aphids.
• Sunflowers can function as a trap crop and draw aphids away from cannabis plants. 

Although companion planting won't be effective in treating plants infested with aphids, it can be a good way to prevent them from taking over your plants. 

2. Proper Airflow and Spacing

Crowded plants and stagnant air are ideal for aphids. To make your grow area less appealing to aphids, just make sure there's proper airflow and spacing.

For instance, maintain adequate space between the plants (at least a foot apart) to allow proper airflow and prevent the aphids from moving from one plant to another. Also, use oscillating fans to keep the aphids away. Inside, the strong air movement makes it hard for aphids to settle down and lay eggs.

Next, cut off the lower leaves to get rid of aphid hiding spots. In addition, get rid of the weak plants since sickly plants get aphid infestation easily. So, discard the sick plants and you'll have enough space for healthy plants. 

3. Regular Inspections

Identifying aphids early on will prevent an outbreak from becoming serious. If you check your cannabis plants regularly, you can take action before the aphids multiply.

Here's how to Inspect your plants for aphids:

• Look under the leaves because aphids love to hide in and around hard-to-see areas.
• Check for honeydew buildup 
• Aphids can be very small so you can use a magnifying glass.

Gently shake the plants over a white piece of paper and this will shake down small aphids easily. 

Check regularly, especially during the vegetative and early flower stages when aphids are most likely to strike. 

4. Using Physical Barriers

Using physical barriers can stop aphids from crawling onto your cannabis plants. These measures work best when you have outdoor grows that will bring aphids from other plants.

Best Physical Barriers for Aphid Prevention:

• Row Covers – A fine mesh cover or row cover prevents aphids from landing on the plants. 
• Sticky Traps – Yellow sticky traps attract and capture aphids and various other pests. 
• Diatomaceous Earth (DE) – This will deter the aphids to a good extent. 
• Mulching with Reflective Materials – Silver or aluminum mulch reflects light, confusing aphids and deterring them from landing.

For indoor growers, using sealed grow tents and air intake filters can prevent aphids from entering the grow space.

How to Get Rid of Aphids on Cannabis Plants?

There are various ways to eliminate aphids on your cannabis plants. Let's go over each method. 

Natural Ways to Get Rid of Aphids

First off, it's best to control the aphids on the cannabis plants quickly, as they can multiply quickly and become a serious problem. Fortunately, you can use many natural and organic ways to kill them without damaging your plants or the environment.

1. Beneficial Insects

One of the most effective methods for naturally combating aphids is to utilize predatory bugs that consume them. These helpful insects are not harmful to cannabis plants, and they can keep aphids in check. Here are a few that can help:

• Ladybugs 

One ladybug can eat 50–60 aphids per day, and both adult ladybugs and their larvae consume aphids. You can purchase them from garden centers or online.

• Lacewings 

Lacewing larvae are voracious aphid hunters. In fact, they are more effective than ladybugs in enclosed grow spaces.

• Parasitic Wasps

These wasps lay their eggs inside aphids, killing them from within. They are most effective for the long-term control of aphids in greenhouses and indoor grows. 

Tips to Use Beneficial Insects:

• Let them go at night or when the sun's just coming up.
• Spraying the plants with water before releasing them helps them stay.
• Skip chemical pesticides — they will also kill useful insects.
• The presence of sufficient predators in your grow area leads to a rapid reduction of aphid populations.

2. Neem Oil

Neem oil can control aphid infestation on cannabis. It is a natural pesticide made from neem tree seeds. This powerful oil extract from the seeds of the neem tree (Azadirachta indica) has been used globally as an organic pesticide for centuries as it's highly effective at killing aphids and preventing them from returning. It is a natural product that does not harm beneficial insects when used correctly.

Neem oil works in numerous ways, making it a great all-in-one pest control product! It suffocates aphids with a coating as it smothers them up when they spray directly on them.

When sprayed directly on aphids, it will disrupt their hormones, preventing them from growing, maturing, and reproducing. It is effective in keeping many other pests away too, including spider mites, whiteflies, thrips, and fungus gnats.

In addition, remember we spoke about how all plants are at risk of fungus when aphids infest them and begin to produce honeydew? Well, neem oil is antifungal, which helps keep diseases like mold away from your plants.

Tips to Make and Apply Neem Oil Spray:

• It is best to make your own neem oil spray even though you can buy mixes online as you'll save money and know exactly what you're using. 
• To make your own neem oil spray, mix a quart of water with a teaspoon of neem oil in a spray bottle.  
• Add a couple of drops of mild liquid soap to this mixture. 
• Mix these ingredients thoroughly and test the mixture on a small area of the plant before spraying it on the entire crop. 
• If everything is fine, you can spray your neem oil mixture on the plants. Make sure to thoroughly spray the leaves, stems, and undersides of leaves as this is where the aphids hide. Repeat the process every 3-4 days until all the aphids are gone.
• The best time to spray is in the evening or early morning to prevent leaf burning from direct sunlight. Do not spray neem oil at the peak sun hours as it may burn the leaves.
• Avoid using neem oil when the plants are too close to harvest (within 2 weeks) since it may leave a bad taste on your buds.
• Do not combine it with other products, like insecticidal soap, unless the mix has been tested. Mixing products will sometimes stress out the plants.

3. Homemade Insecticidal Soaps

Insecticidal soaps work by breaking down aphids' protective outer coating, causing them to dehydrate and die. Unlike synthetic pesticides, these soaps are safe for cannabis plants and won't harm beneficial insects if used properly.

To make your own spray, mix a quart of water with a tablespoon of mild liquid soap like castile soap. You can also add ½ teaspoon of cayenne pepper or garlic juice. Next, mix the ingredients in a spray bottle. Now, shake well and spray directly onto aphids and affected plant areas.

Make sure you focus on the leaf undersides where aphids hide. Rinse the plants with clean water after a few hours to prevent leaf damage. Repeat every 2–3 days until aphids are gone.

Chemical Treatments for Aphid Control

If natural remedies are ineffective against severe aphid infestation, chemical treatments may become necessary. They can work but you should use them as a last resort method due to risks to plant health, beneficial insects, and human consumption. 

There are various organic pesticides you can use to kill aphids. Before using synthetic ones, you should certainly try these if you want to be safe. 

Organic pesticides are an effective compromise between natural treatments (such as neem oil) and chemical ones. If used the right way, they come from natural sources, decompose quickly in the environment, and are not harmful to beneficial insects, humans, and pets.

In short, organic pesticides are a powerful yet environmentally friendly way for cannabis growers to get rid of aphids without contaminating the buds or harming the ecosystem. Here is a list of the best organic pesticides for aphids.

1. Pyrethrin-Based Sprays

Pyrethrin is a natural insecticide sourced from chrysanthemum. The pesticide attacks the nervous system of the aphids causing paralysis and death. Unlike other synthetic insecticides and pesticides, pyrethrin breaks down in the sunlight and reduces the risk of contamination. 

Benefits of Pyrethrin Sprays

• Pyrethrins kill aphids on contact for fast results.
• Breaks down quickly and doesn't leave behind a residue on the plants.
• Using the right pesticide and applying it correctly can help you achieve great results. 

How to Use Pyrethrin Against Aphids:

• Spray directly on the leaves, making sure to coat leaves, stems, and undersides where aphids hide.
• Apply in the evening or early morning to avoid harming beneficial insects like bees.
• Use sparingly – Pyrethrin can harm beneficial predatory insects like ladybugs if overused.
• Avoid using during flowering to prevent residue buildup on buds.

Remember that pyrethrin is toxic to bees when wet. If growing outdoors, spray when pollinators are not active (early morning or dusk).

2. Horticultural Oils

Horticultural oils are plant-based or mineral-based oils that work by smothering aphids, blocking their breathing pores and leading to suffocation. These oils are highly effective for outdoor or greenhouse cannabis setups.

Types of Horticultural Oils:

• Canola oil is a kitchen oil that you can mix with water to kill aphids.
• Soybean oil can deploy the same tactic as neem oil to disrupt pests.
• Mineral oil is a very light oil that will coat soft-bodied insects like aphids.

How to Use Horticultural Oils Against Aphids:

• Combine it with water (typically a 1-2% solution).
• Make sure to spray the aphids directly.
• Use in the morning or evening so that the leaves don't get burnt.
• Repeat the process each week until all pests are gone. 
• Don't use horticultural oils on stressed or young cannabis plants. If too much oil builds up, it can block the stomata (pores), which reduces photosynthesis.

3. Spinosad

Spinosad is a natural pesticide derived from soil bacteria (Saccharopolyspora spinosa). It affects the nervous systems of aphids, making them paralyzed and dead in a few hours. Spinosad does not have harmful effects on humans, pets, and beneficial insects once dry, unlike other chemical pesticides, making it safer for organic cannabis growers.

Benefits of Spinosad

• Spinosad has the potential to kill aphids in just 24 hours if you use it properly. 
• It is a safe product for mankind and our beloved pets and is unlikely to harm anyone including beneficial insects like bees, and ladybugs (after drying).

How to Use Spinosad Against Aphids

• Spray the solution directly on the aphids and affected parts of the plant.
• Use it in the early morning or evening hours 
• Repeat once a week until the aphids are completely gone.
• You can use this during flowering but don't directly spray the buds.

Even though organic pesticides are safer than synthetic ones, they should still be used sparingly to stimulate an ecosystem balance within your growing space.

Best Practices for Using Organic Pesticides

• Make sure to use different treatments for aphids so that they do not develop resistance. Use pyrethrin, spinosad, and horticultural oils in rotation.
• When all else fails, you should apply organic pesticides i.e. when you have already tried all natural methods like neem oil, beneficial insects, etc.
• Check how your plants react. Some cannabis strains have a greater sensitivity. Test on a small area before widespread application.

Summary: Aphids on Cannabis? How to Spot, Stop, and Prevent These Pesky Pests for Good!

Aphids may seem small and harmless but they can wreak havoc. Before they become a nightmare, make sure you control them. 

These pesky, sap-sucking insects weaken plants, spread diseases, and attract even more trouble in the form of ants and sooty mold. If don't treat your plants on time, they can experience stunted growth, poor yields, and even total crop failure. But the good news? You have plenty of effective ways to fight back! 

Remember, you need to prevent them because it's very difficult to eliminate them. 

You can use aphid-repelling herbs and companion planting along with proper airflow and plant spacing. You can also use some insect nets and check plants regularly to catch aphids early on.

Some growers use aphid predators including ladybugs, lacewings, and parasitic wasps that can easily be found online. Beneficial insects like ladybugs can help you to keep the aphids at bay. Or, you can get rid of aphids by using neem oil and homemade insecticidal soaps if they ever reappear.

Organic pesticides can also help if the infestation becomes too large. Pesticides such as pyrethrin, horticultural oils, and spinosad are safe and effective and won't contaminate your cannabis as long as you take care and limit their usage so that it does not harm beneficial bugs.

Finally, you can also use synthetic pesticides if the infestation is extremely severe and no other methods have worked. We haven't discussed them in this article as you can eliminate aphids easily with the other techniques. 

The best way to combat aphids is to have healthy plants in the tent as they will have better immune systems. If you use soil rich in nutrients and take care of the watering needs of the plant, you'll be well on your way to avoid pests. 

Just remember that aphids may be relentless but you are smarter stronger and better equipped against them. You can keep your cannabis plants healthy and free of aphids with preventative measures, natural remedies, and organic treatments.

So, with a clear plan of action and optimally prepared growing conditions, there are many effective ways that can help you keep your plants healthy and free from aphids. Your plants (and your future harvest) will thank you.