How to Identify the Most Common Cannabis Pests?

Mother nature is beautiful. Except she’s also kind of gross and at times, highly inconvenient. And since cannabis is a plant, it is subject to pests and parasites. Whether marijuana is grown indoors or outside, it cannot escape the circle of life, and apparently, humans aren’t the only ones interested in consuming cannabis. Watching tender young cannabis seedlings or clones grow into vigorous, mature plants that in turn produce sticky, trichome-covered buds is almost magical, especially when the buds are properly cured and shared with friends who rave about the dankness. But, seeing healthy cannabis plants succumb to a pest infestation can be a terribly frustrating tragedy. In the context of plants, the term “pest” refers to any organism that can cause disease or damage to plants grown for crops. Fortunately, cannabis growers don’t need to re-invent the wheel when it comes to addressing plant pests. Preventative measures vary for outdoor grows versus indoor grows. Cannabis plants grown outdoors will benefit from natural checks and balances that limit many insect and fungus infestations. Natural pest predators, such as ladybugs as well as the wind and rain, can work in the grower’s favor. The indoor grow environment doesn’t have these checks and balances, allowing pests to thrive and spread much faster if not properly managed. An important part of plant monitoring is identifying the pest in question so that it can receive proper treatment. Here are some of the most common cannabis pests.

Spider Mites

These guys are probably the most common of all pests and can cause the biggest headache. Spider mites don’t play; they reproduce rapidly, reach full maturity in a matter of days, and binge on plant material until chlorophyll is depleted and the plant is dead. It doesn’t take long for a spider mite spotting to turn into a full blown infestation and the demise of an entire cannabis harvest. A common way to spot spider mites is by misting a cannabis plant with water which will reveal the protective cobwebs that they weave.


Easy to miss, aphids are tiny, quick, and devastating. Like spider mites, they reproduce quickly and feast on the cannabis plant matter. They are especially damaging to indoor gardens that lack the natural aphid predators outdoor gardens can harness for protection. They produce a “honeydew” substance that leaves sticky residues and attracts ants, which often “farm” aphids for their honeydew.


Rather than posing a direct threat to cannabis plants, ants are indicators of other problems since they are attracted to aphids or whiteflies. Additionally, as burrowing insects, ants can damage the cannabis root systems.

Grasshoppers and Crickets

Pot lovers by nature, these insects will make the cannabis plant their primary food source without quick and effective intervention. Crickets and grasshoppers typically feast at night and leave behind a whole lot of damage for growers to discover in the morning. While birds love to eat these bugs, they must dig through the soil to get to them, and that can cause damage to root systems.Grasshoppers (and sometimes locusts, which are basically just grasshoppers with wings) will hapily eat your cannabis leaves and live among the branches. If you see this pest, it’s a good idea to get rid of them before they build up in numbers!


Like grasshoppers and crickets, caterpillars are very attracted to cannabis, and their insatiable appetites can destroy the crop. Borer caterpillars go unnoticed because they burrow through the plant, hollowing it out and killing it before growers realize what’s happening. Caterpillars can be easy to spot and remove (mostly by hand), but it’s important to remember that these cute little critters can be fatal to your plant, causing open wounds that can invite crop-threatening diseases.

Leaf Miners

These insects are creepy and make me a little paranoid about eating anything leafy. They burrow through the cannabis plant and mine the leaves of cells and nutrients. In their wake, they leave behind brown or white streaks through the leaf tops. The adults leave their larvae under the leaves, and those babies grow up to be just like their creepy, burrowing parents. Unfortunately, the best remedy for these bugs are your hands since most pesticides that target leaf miners are more dangerous than they are beneficial. Yep, that means you’ve got to find ‘em and squish ‘em. The leaf will appear as though squiggly lines have been drawn on it, but the damage is in fact inside the leaf.

Fungus Gnats

From their larval-hood to adulthood, these microscopic insects love to eat the cannabis plant. They start by eating fungus near the plant’s base, but steadily eat through the roots. This can be devastating for plant growth and soil drainage. While gnats cause less plant damage than aphids, these small flying insects can spread diseases and fungi. A good way to monitor for gnats and other flying insects is to hang a few sticky traps around your cannabis plants. When flying insects land on them, they get stuck and die. By regularly checking the sticky traps, you can easily determine if flying insect pests are getting into a grow and multiplying.

Slugs and Snails

Simultaneously cute and disgusting, these common garden pests eat cannabis plant matter and can eventually do a lot of damage. They aren’t particularly discreet, though. They leave streaks of shiny slime everywhere they go. Like I said. Cute and disgusting. Slugs and snails are considered to be a minimal threat to plants once they have taken root and begun to mature, but during the early stages of growth, they can be fatal to a cannabis crop. They munch at seedlings and snuff out cannabis plants before they’ve had a chance to grow.


These tiny, flying insects love to chow down on cannabis. They live beneath cannabis leaves, and, because of their size, are not easy to see. Whiteflies can be particularly dangerous because of their ability to spread disease. As fliers, they are extremely mobile, and once they show up, they can take down an entire harvest. If whiteflies are present and you shake an affected plant, you should be able to hear a buzzing sound before you see them. Like most insect pests, whiteflies suck juices out of the plant.

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These tiny bugs thrive on the cannabis flower. An infestation of them can ruin the crop’s ability to fully mature. Like whiteflies, thrips are notorious for spreading diseases which can be even more detrimental to the plant than the thrips’ appetite. Adult thrips have wings, and they leave tiny dots similar to mites where they suck juices from the leaves. Their attacks on flowers leave silvery-looking patches.

Mealy Bugs

These insects are not a problem in small numbers, but an infestation could overrun a harvest. Mealy bugs are small and live in the plant’s crevices. Because of their tiny size, mealybugs can be difficult to accurately identify without a loupe or other magnifying device. To the naked eye, mealybugs look a lot like powdery or downy mildew, creating cottony, “mealy” patches on plants. They make their presence known by leaving behind gifts of cotton-like balls. These insect-hand-crafted gauze balls can cover a cannabis plant, and the presence of the mealy bugs can cause plant discoloration.

Root maggots

As the name implies, root maggots are larvae that feed on your plant’s roots. Like fungal gnat larvae, you may not notice the pest until you see evidence of its damage which will be a weakening of the plant and it may appear as nutrient deficiencies or too much water. A little digging in the soil at the base of your cannabis plants could reveal the presence of these damaging pests.

Natural Solutions to Pests and Parasites

Despite her inconvenience, mother nature is also a force of balance. Ecosystems work to create and sustain life because each part of that system contributes to its overall wellbeing. So here is a list of critters to welcome to a cannabis friendly ecosystem. Keep in mind that these are pretty much exclusive to outdoor grows.

  • Amphibians are natural predators for snails and slugs.
  • Aphid midges are great natural predators for over 60 types of aphids.
  • Damsel bugs eat lots of pests including caterpillars, leafhoppers, thrips, and aphids.
  • Ground beetles binge eat on slugs, snails, and cutworms.
  • Lacewing larvae and adults thrive on caterpillars, mealybugs, thrips, whiteflies, and aphids.
  • Lady bug larvae and adults feast on mites, mealybugs, and aphids.
  • Birds of prey are natural predators for mice, rats, and gophers.
  • Sunflowers are pretty, covering, and natural repellants to cutworms.
  • Wasps and praying mantises are natural predators for caterpillars.

Sometimes introducing natural predators to a cannabis grow isn’t an option or enough. Here are safe ways to deter pests from your cannabis:

  • Neem oil has been regarded as an incredibly potent and versatile pesticide for centuries. A spray containing this oil, organic soap, and warm water can ward off all kinds of insects.
  • Salt spray is an effective repellant for spider mites and other insects because it dehydrates the bugs and their larvae.
  • Citrus oil can be used in combination with cayenne pepper, soap, and/or water to create a natural pesticide for slugs and ants.
  • Onion and Garlic sprays are a natural repellant for most insects.
  • Scarecrows or reflective objects are good, reversible deterrents for birds. Once the seeds have sprouted, you can remove these items so birds can help you get rid of other pests.
  • Fences are the best deterrent for large mammals including dogs, cats, deer, and humans.
  • Diluted dish liquid is a good way to get rid of grasshoppers and crickets.
  • Cornmeal is a safe way to deter ants from your plants. While ants are natural predators for whiteflies and aphids, they also threaten cannabis root systems, so apply cornmeal to the soil to keep them away.

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