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.
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!
- 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
- 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! ]]>