aphids on marijuana plants


How to Identify Aphids on Cannabis Plants (also called greenflies and blackflies)

Aphids are soft-bodied insects which can appear white, green, yellow, black, brown and red, depending on their stage of life and where you live. Because they’re so widespread they can be a cannabis pest almost anywhere in the world!

Aphids look very different depending on their stage of life. In this picture, the bigger, rounder bugs are adult aphids, while the white, smaller, thinner bugs are young aphids (nymphs). Note: If you’re seeing white bugs that look like tiny fat worms, you may actually have thrips.

Sometimes the aphids that attack marijuana are dark colored or black. This bud is aphid city!

Sometimes when growers see tiny black flies or green flies on their cannabis, they’re actually seeing aphids with wings. Winged aphids can be dark or pale, and colors include green, red or yellow. However, the general body shape of the bug is usually pretty similar whether the aphids have wings or not.

Because many aphids that attack cannabis are green, sometimes people don’t recognize aphids when they’re a different color (like these young aphids which appear red)

These aphids from Europe are pale green with dark legs and red eyes

Aphids are a common cannabis pest. Adults are usually small and oval-shaped and may have visible wings or antennae. Nymph aphids are thin/long and usually white or pale. Because nymphs are so small, they may look like little white specks or eggs.

Aphids pierce cannabis leaves with their sucking mouth-parts and feed on the juices inside. They usually occur in colonies located mainly on the undersides of stems and leaves. If a cannabis plant becomes heavily-infested, its leaves can turn yellow and/or wilt due to the excessive stress and leaf damage.

“Honeydew” and Black Sooty Mold

Another problem with aphids is they produce large amounts of a sweet substance known as “honeydew,” which is a sugary liquid waste. Honeydew drops from these insects attract a type of fungus called sooty mold. Sooty mold can grow on honeydew deposits, accumulating on the leaves and branches of your plant and turning them black. Not only does this mold discolor the plants and somewhat hinder normal plant processes, sooty mold on buds can make them unsafe to smoke. And just to be an extra pain in the butt, the drops of sweet honeydew can also attract other insects such as ants.

What Causes an Aphid Infestation?

Your plant can become infested when winged “colonizer” aphids land on the plant and lay eggs. Although you may not see the winged version of an aphid actually eating your plant, they are still dangerous because they can lay eggs and start a new aphid colony! Winged aphids are sometimes called “blackfly” or “greenfly” bugs depending on the color (because they are often black or green/yellow, and they look like tiny flies).

Aphids are sometimes called “Green Flies” or “Black Flies” when they have wings, but the general body shape is the same. The winged versions appear when the aphid colony gets too numerous and these bugs use their wings to fly away and lay eggs on other plants. This “black fly” is actually a winged aphid.

This “green fly” is another color variation of a winged aphid

It’s difficult to prevent aphids from getting to your cannabis plants outdoors as just a handful of winged aphids is all it takes to start an infestation. The eggs soon hatch into a juvenile form of aphids called “nymphs,” which happily start munching on your plant.

This grower started seeing white specks on their buds and thought it might be mold or bud rot. The specks were actually white aphid nymphs. Click the picture for a closeup!

Immature aphids (nymphs) usually appear white and feed on plant sap while they gradually increase in size.

The aphid nymphs mature in 7 to 10 days and shed their skin, leaving silvery exoskeletons behind on your plants. Note: If you see tiny white bugs but they look round, fat and more worm-like than these ones, you may actually have thrips.

The bottom center aphid is actually in the middle of shedding its exoskeleton in this pic.

After reaching their wingless adult form (aphids don’t grow wings when actively colonizing your plant) they are soon ready to give birth to live young and start the process over again. Most aphids in this form are female, and each one is capable of producing dozens of offspring.

Because of their quick reproduction, a few winged aphid “colonizers” can lead to hundreds or even thousands of aphids on a plant in just a few generations. A full-blown aphid infestation can get out of control in just a few weeks!

Aphids often keep reproducing on the plant until the plant becomes so stressed (or the conditions become so crowded) that the plant can no longer support their ravenous appetites. At that point, some of the aphids start being born with wings, and these winged aphids fly off in search of a new host, starting the process over again on a new plant victim.

Solution to Aphids: Get Rid of Them Quick!

Avoid using nervous system insecticides, such as malathion, Dursban (chlorpyrifos), and Orthene (acephate). They are labeled for use on many shade trees and ornamental plants for aphid control, but are not safe to use on cannabis. If something isn’t safe to be used on edible plants, then chances are it’s not safe to use on cannabis.

1.) Check regularly for signs of aphids

The best way to prevent an aphid infestation is to catch it as soon as possible. When growing outdoors it’s pretty difficult to predict when winged “colonizer” aphids will appear, so it’s incredibly important to examine your plants at least weekly to make sure they don’t become infested while you’re not paying attention.

Examine the bud area and undersides of the new leaves for clusters or colonies of small aphids (or any other types of bugs). The presence of these colonies indicates that the aphids are established on the plants and their numbers will begin to increase rapidly.

2.) Remove or Spray Off As Many Bugs As Possible

If your plant is heavily infested, it’s a good idea to try to cut down their numbers in every way possible. Depending on the infestation, one way to do that may be to simply move your plants outside and spray as many bugs off as you can with a power sprayer. It’s also a good idea to remove leaves and buds that are heavily infected.

If possible, spray off as many bugs as you can!

3.) Insecticidal soaps

Fatty acid salts or insecticidal soaps can be a good choice against aphids. They weaken the outer shell of aphids but are safe to use on your plants and they don’t leave much of a residue.

With soaps, coverage is very important as it does not stay on your plant for long, so follow-up applications may be necessary. Although this is considered safe, avoid getting any on your buds!

4.) Neem Oil

Neem Oil will leave an unpleasant taste/smell on buds when used to treat flowering plants, so again, don’t let this stuff get near your buds! There’s also some evidence Neem oil may be harmful to humans so use with care! That being said, Neem oil is an all-natural remedy that is very effective against many different types of bugs and mold. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly, since neem oil and water can separate easily.

5.) Spinosad

Spinosad Products (safe & organic) – Spinosad products are organic and completely harmless to pets, children, and plants. Spinosad products can be used directly to kill aphids on contact and should be sprayed liberally anywhere you see aphids and especially under the leaves. Although maybe not as strong against pests as some of the more harsh insecticides, it does work and it’s very safe for plants, animals and humans!

Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria (actinomycete Saccharopolyspora spinosa) and kills aphids via ingestion or contact by effecting the insect’s nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to aphids, but is less toxic to many beneficial insects and spiders.

Note: Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. Anything left over will be waste.

You will need a mister (also called a “One-Hand Pressure Sprayer”) to cover all the leaves evenly when spraying them with spinosad products.

6.) Essentria IC3

Essentria IC3 Insecticide is a mix of various horticultural oils that is organic and safe for humans. It is often marketed as a “bed bug killer” but it can be effective against aphids when the plants are treated regularly. Unfortunately it only stays effective on the plant for about 8 hours so you will want to either apply this daily or combine with other options. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

7.) Beneficial Insects

Beneficial insects, such as lady beetles, lady bugs, and lacewings may eat large numbers of aphids and are welcome guests in the garden. Although you can order ladybugs to release around your plants, they tend to fly away in just a day or two. Additionally, the reproductive capability of aphids is so great that the impact of the natural enemies may not be enough keep aphids at or below acceptable levels after an infestation has already gotten started.

Ladybugs are good to have around the garden – they eat aphids and other annoying cannabis pests!

Many other “lady bird” type beetles also eat aphids

This scary looking black bug is actually a young ladybird larvae, so don’t kill it! They devour aphids as youngsters too, so it’s good to let them do their thing ?

Good bug! Eat those aphids!

8.) Get rid of ants if you see them!

In some cases, ants naturally “farm” (tend to) aphids in the wild in order to collect their honeydew. How crazy is that? Ants can actually be helping keep your aphid numbers up! So for some cannabis growers, controlling an ant problem can actually help control an aphid problem.

If you have ants, get rid of them! They can make an aphid problem worse!

Plant Symptoms

  • Bronze or brown patches
  • Brown or slimy roots
  • Brown or yellow leaf tips/edges
  • Buds dying
  • Buds look odd
  • Bugs are visible
  • Curling or clawing leaves
  • Dark leaves
  • Drooping plant
  • Holes in leaves
  • Mold or powder
  • Pink or purple on leaves
  • Red stems
  • Shiny or smooth leaves
  • Spots or markings
  • Twisted growth
  • Webbing
  • Wilting leaves
  • Yellow between leaf veins
  • Yellow leaves

This page is part of our Plant Doctor series. You can use our tool to filter by symptom and help diagnose your plant.

Learn how to identify and get rid of aphids (aka greenflies /blackflies) and prevent them from ever attacking your cannabis again!

How To Spot, Treat, And Prevent Aphids On Cannabis Plants

Aphids are a common pest affecting cannabis growers around the world. Read on for a detailed look at what they are, how to spot them, and how to control and protect your cannabis plants against an aphid infestation.

Cannabis gardeners, like regular gardeners, are always on the lookout for pests that might hinder the development of their plants.

In this article, we look at aphids, a common garden pest that can have detrimental effects on your cannabis grow. We’ll show you exactly what aphids are, how to spot them on your plants, and how to control/prevent them.

For more articles like this, remember to bookmark our blog. To order the highest quality cannabis seeds direct to your door, visit the Royal Queen Seeds webshop today.

For more information on cannabis pest control, check out this previous article on our blog.


The term aphid is used to refer to a group of small sap-sucking insects that count as one of the most destructive pests on cultivated plants.

Aphids can vary in size from roughly 1 to 10 millimetres and can be green, black, red or white in colour. The most common kind of aphids found in home gardens are usually green and about 1 millimetre long.

They have two whip-like antennae at the tip of the head and oppositely a pair of tube-like structures, called cornicles.

Winged female aphids usually hatch at the beginning of spring and give birth to more female nymphs. Within a few weeks, these nymphs give birth to more young. This process is repeated several times, allowing aphid numbers to rise dramatically in a short amount of time.

By the end of the summer, aphids develop sexual forms (males and females) and mate to produce overwintering eggs. Most aphids, except for the sexual forms, do not need to mate in order to reproduce and are able to produce live young.

There are over 4,000 aphid species found around the world. Some aphid species are capable of developing wings.


Aphids can usually be seen on the leaves and stems of cannabis plants. Green varieties may be harder to spot. They especially like hiding on the underside of leaves, away from direct sight.

Aphids feed by sucking sap from plants, leaving behind a thick, sticky substance called honeydew, which can promote the growth of a black, sooty mould. Honeydew also attracts ants, which may protect aphids from any predatory insects and thereby make an infestation even worse.

When feeding, aphids can cause leaves to curl, wilt or yellow and stunt plant growth. Aphids are also capable of transmitting diseases which they pass on when they feed on new plants.


Small aphid populations are usually not a big concern. However, aphids are able to reproduce extremely quickly and large infestations can have a huge impact on the health of your cannabis plants and their ability to develop.

Aphids are introduced into gardens by winged “colonisers” which quickly lay eggs on new plants they wish to colonise. While it’s always best to prevent a pest infestation than control one, aphids can be particularly hard to prepare against. Outdoor gardens are usually more at risk of an aphid infestation.

As we mentioned earlier, winged female aphids usually hatch in spring while new female and male aphids usually lay overwintering eggs at the end of summer. If you want to protect your garden against any kind of pest infestation, it’s always best to ensure that your grow environment isn’t “attractive” to pests.

Most garden pests like warm, humid conditions and stagnant air. It’s therefore always important to ensure your grow room is kept at the right temperatures (between 20 and 25ºC is ideal) and you should install a few fans or a ventilation system to ensure plenty of airflow.

However, to best protect against an infestation, try some of the following tips and keep an extra eye out for aphids during spring and late summer.


If you spot aphids on your plants, a good first step to dealing with the infestation is to prune off any infested areas and disposing of them immediately.

Once you’ve pruned the plants, you’ll also want to hose them down with water, or a water-vinegar solution that will kill any remaining insects.


Ladybugs, hoverfly larvae, parasitic wasps, aphid midge larvae, crab spiders, and lacewings all naturally prey on aphids and many other pests (such as spider mites and whiteflies).

We recommend introducing some of these insects to your garden during spring and late summer to best prevent an infestation. If you’ve already detected aphids on your plants, it’s usually too late to rely on predatory insects.

Instead, follow some of the other tips below and, once you’ve dealt with an infestation, reintroduce predatory insects into your garden to prevent another infestation in the future.


As with any other garden pest, we recommend staying away from chemical pesticides as they usually aren’t safe to use on cannabis plants. Instead, try using some of these options.

Essentria IC3: Combining a variety of horticultural oils, Essentria IC3 is an organic insecticide we always recommend having on hand. It can be directly applied to plants and can help to control many regular pests, including spider mites, whiteflies, and aphids. However, it usually remains active for 8-12 hours, so we always suggest you use it daily until an infestation has been completely controlled.

Spinosad: All Spinosad products are completely organic and should form part of every cannabis growers grow tools. Like Essentria, Spinosad can be sprayed directly onto your cannabis plants and will kill most garden pests on contact. Once you’ve taken care of an infestation you can also add Spinosad to your plants’ water supply to protect them from pests in the future.

Insecticidal soaps: Insecticidal soaps are ideal for spot-treating infected plants. They can take care of most regular garden pests (like spider mites and whiteflies) but shouldn’t be applied directly to any cannabis buds. Like with Spinosad and Essentia, we suggest using insecticidal soaps at least twice to ensure you’ve completely removed all aphids on your plants.


Some gardeners swear by using horticultural and essential oils to treat garden pests like aphids. Neem oil is very commonly used in pest protection, but there are a variety of other oils rumoured to do the trick as well, including eucalyptus, rosemary, lemon, and cinnamon oil.

Simply mix any of these oils with water and apply them evenly to your plants with a mister. Most essential oils contain properties that will affect pests on contact. Just be careful not to get any aromatic oils on your buds as they will affect their aroma profile.

Alternatively, you may also want to treat your plants regularly with horticultural oils. We generally recommend using vegetable oils, such as canola, soybean, or cottonseed. These are usually less likely to alter the smell of your buds.

Aphids are a common garden pest that can have detrimental effects on cannabis plants. Click here to learn how to protect your cannabis plants against aphids.