How to Rid Your Cannabis Plant of Aphids

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In Common Marijuana Insects and Pests to Look Out For we mentioned that aphids are one of the most common pests that can plague your marijuana. They are also one of the most annoying, they will appear on your plants without warning since you’re likely to pick them up just about anywhere. 

Aphids are a group of insects that destroy plants by sucking nutrient-rich sap, particularly from soft stems, branches, buds and fruit of almost all kinds of garden plants. There are lots of kinds of aphids and each can appear in different colors, so it is important for you to identify them correctly so you don’t mistake them for something else.

How to identify aphids

Aphids are soft-bodied insects around 4 to 8 mm in length. They come in various colors: white, black, brown, gray, yellow, light green, even pink. The most common marijuana aphid, the Phorodon Cannabis, which somehow evolved to specifically ravage the Cannabis plant, comes in a greenish or pale yellow color.

If you want to be sure that you’re dealing with aphids, check the rear end of these pear-shaped pests for two thorn-like protrusions called cornicles. Mature aphids can either be wingless or winged, with the winged ones appearing a bit darker while nymphs are thin, long and pale colored. Since they feed on the sap and plant fluids, they also leave excretions that appear as sticky beads on the leaf. This sweet substance attracts ants but also fungus and mold, adding to the damage caused by the aphids. 

Why are aphids bad

Aphids “drain” the life out of your plant, especially the weakened ones, by piercing its softer parts, drinking its nutrient-rich sap. A plant with an aphid problem will grow slower, have a wilted appearance with yellowing leaves. Not only that, the sugary, liquid waste they leave also attracts a fungus called sooty mold which turns the leaves and branches of your plant black. This not only affects normal plant processes, it also makes your marijuana unsuitable for smoking.

When might you notice aphids

You can often find aphid colonies underneath the leaves and stems of your plant but sometimes you’ll only notice an aphid problem once you have a full-blown infestation. A single aphid can produce as many as 80 offspring in a week while nymphs, which are difficult to spot, can grow into a reproducing adult in just around 7 days. 

Aphids need a warm environment, around (65°-80°F), to multiply this quickly. This is why maintaining the right temperature in your grow room helps a lot in preventing infestations. 

Organic methods to deal with aphids

It’s totally possible to get rid of aphids using natural and organic methods. Here are some of the more effective ways of aphid pest control popular with cannabis growers.

  • Natural predators – These are insects that attack or eat aphids but will not harm your cannabis plant. Some of these are the green and brown lacewings, ladybugs, hover flies, midges, big-eyed bugs, damsel bugs, soldier beetles, and blister beetles. These insects, which are typically found in the garden, are also effective in fighting other pests, making them your best bet for aphid control before resorting to pesticides.

  • Spinosad & Soap spraysSpinosad is a natural, broad-spectrum pesticide made of soil bacteria that is toxic to most insects. Meanwhile, soap sprays dissolve the fatty acids on the aphid’s exoskeleton and block its breathing pores, but the spray will only work on contact with the aphid. Use these sprays if you’re unable to solve your aphid problem using natural predators. 

  • Horticultural sprays – These contain petroleum, paraffinic, mineral or neem oil and work similarly to soaps sprays, blocking the aphid’s breathing pores and disrupting the water balance of its eggs. However, these should only be used when the surrounding temperature is around 40 to 75 degrees Fahrenheit so that the oil can evaporate at a faster rate and not damage the plant’s leaves.

  • Diatomaceous earth – This is a powder made of fossilized remains of aquatic microorganisms called diatoms. These diatoms scratch the waxy coating of the aphids, causing them to dry out. Diatomaceous earth can cause health problems when accidentally inhaled, so you need to wear a mask when handling it.

  • Pyrethrin – This pesticide is extracted from the flowers of the chrysanthemum plant and is considered organic. However, pyrethrin can cause allergic reactions when it gets into the lungs which is why this is typically only used in large scale infestations.

Non-organic methods to deal with aphids

Since natural methods for getting rid of aphids are already fairly adequate, the use of synthetic pesticides are already practically obsolete. Consumers nowadays also overwhelmingly prefer organically-grown cannabis, since non-organic ones grown with chemicals and pesticides are known to cause headaches, hangovers, and greater burn in the throat and lungs. In fact, laws in some states already prohibit the use of non-organic pesticides in growing cannabis. However, because they are really effective, some illegal growers still use synthetic pesticides as a nuclear option for really bad infestations. Here is a list of active ingredients in some non-organic pesticides that are already banned for use on cannabis:

  • Abamectin
  • Acephate
  • Aldicarb
  • Azoxystrobin
  • Bifenthrin
  • Boscalid
  • Brodifacoum
  • Bromodiolone
  • Carbaryl
  • Carbofuran
  • Chlorantraniliprole
  • Chlordane
  • Chlorfenapyr
  • Coumaphos
  • Cyfluthrin
  • Daminozide
  • DDVP (Dichlorvos)
  • Diazinon
  • Difenacoum
  • Difethialone
  • Dimethoate
  • Dimethomorph
  • Ethoprop(hos)
  • Etofenprox
  • Fenoxycarb
  • Fipronil
  • Fludioxonil
  • Imazalil
  • Imidacloprid
  • Malathion
  • Metalaxyl
  • Methiocarb
  • Methomyl
  • Methyl parathion
  • Mevinphos
  • Myclobutanil
  • Naled
  • Paclobutrazol
  • Propiconazole
  • Propoxur
  • Spiroxamine
  • Tebuconazole
  • Thiacloprid
  • Thiamethoxam

Frequently Asked Questions on Aphids

How fast do aphids reproduce?

In warmer environments, an aphid is able to produce around 80 offspring in a week. Nymphs, which are difficult to spot, can grow into a reproducing adult in just around 7 days. 

What are signs that you have an aphid infestation?

While groups of aphids are immediately visible to the naked eye, other signs of an infestation are sticky liquids on the leaves, and a wilted appearance with yellowing leaves.

Are aphids harmful to cannabis plants?

Aphids feed on the plants sap, depriving it of nutrients and liquids. Colonies of aphids can drain your cannabis plants, slowing its growth and even killing it.


Aphids are really pesky cannabis pests but they are totally manageable and preventable. A good way to prevent an aphid attack from even happening is to keep your plants healthy and maintain an adequate growing environment since the right temperature and humidity will make it inhospitable for aphids and other pests. Once you notice a pest problem, try bringing in some natural predators first and follow up with diatomaceous earth. If the problem persists, proceed with pesticide sprays but use as little as possible since any chemical you spray on your cannabis plant can potentially influence its taste and smell.

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