Common Cannabis Pest Identification – IncrediGrow Garden Centre

Your order may qualify for free shipping! Click for details

Common Cannabis Pest Identification

General Advice:

  • It is not recommended to spray cannabis while it is in flower. Just because a pesticide is listed as being “food safe” doesn’t mean you want to smoke it!
  • Never spray anything on your plants with the lights on. This includes water!
  • ALWAYS inspect and quarantine new plants before introducing them to your garden, even if the grower assures you that they’re bug free. What is an unnoticeable problem in their garden could become difficult to manage in your garden. 
  • You can bring indoor plants outside, but bringing outdoor plants inside is risky. 
  • If you introduce hydrogen peroxide to your root zone, you need to continue using it for your entire grow. Enzymes can be introduced without creating a dependency.
  • Most sprays require applications at two-week intervals because the eggs are protected.
  • Ladybugs require multiple applications as they tend to fly away. 
  • You, your children and especially your pets can carry pests from outdoors. Pets should be barred from your grow room and humans should shower and change their clothes after coming in from outside. Always wash your contaminated clothes in hot water.

Notes on Beneficial Insects: 

  • Pyrethrins will kill your beneficial mites and ladybugs. 
  • Diatomaceous earth will kill your beneficial mites and ladybugs.
  • Sticky traps will kill your ladybugs.
  • Hydrogen peroxide will kill your nematodes, beneficial mites and ladybugs.
  • Mosquito dunks will not kill adult insects. They will also not harm your nematodes.


Winged Colonizers

Identification: Black, green, brown, orange or yellow insects with long legs and pear-shaped bodies, generally found on stems and on the underside of leaves. Some individuals have wings. Immature aphids (nymphs) usually appear white. You may also see ants tending to the aphids.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, N-Force, water jets, hand-picking. 

Biological Control: Ladybugs
Natural aphid repellents: Catnip, garlic, chives, onion, and allium. However, onions and chives may attract thrips.

Prevention: Keep your outdoor plants outside. Remove rose bushes from your yard if possible. Do not allow ants to enter your grow room, as they may be carrying aphid eggs. 


Identification: White and black, slender, long insects that tend to cluster. They will flip their tails back and forth rapidly when disturbed.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, N-Force, water jets.
Biological Control: Cucumeris, stratiolaelaps, potentially ladybugs. Nematodes will kill the larvae in the soil, but will not control the bulk of the infestation because it is located above-ground.
Prevention: Inspect and quarantine any new plants before adding them to your garden. Remove weeds, grass and crop debris from yard. If you have flowers in your yard, constantly dead-head them when the blossoms die. Do not allow dandelions to grow in your yard.
Notes: Eggs are laid inside of a small hollow that the female digs in the stem of the plant, where they will be protected from pesticides and predators until they hatch. Therefore, you may require cyclic applications (every two weeks) of your control method until the problem is solved. 

Spider Mites

Identification: Small red arachnids that may look like rust spots on your plants. By the time you see webs, your infestation is advanced.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, water jets, N-Force, pruning infested portions and burning them.
Biological Control: Cucumeris, persimilis, stethorus, fallacis.
Prevention: Spider mites love dusty and water-stressed plants. Please ensure that your grow room is not dusty and that you are properly watering all of your plants. 

Fungus Gnats

Identification: Often confused for fruit flies. Fungus gnats are small, slender black flies. They may suddenly appear in large numbers.
Control - Adults: Pyrethrins, insecticidal soap, yellow sticky traps, diatomaceous earth.
Control - Larvae: Hydrogen peroxide (mix 1:4 with water), mosquito dunks.
Biological Control - Larvae: Mosquito Dunks, nematodes

  • Ensure that you have no leaks in your watering system, and that all sinks and nearby toilets are kept clean and that garbage and compost is removed. 
  • Do not leave open beverage containers around. No juice boxes, no beer cans and no pop bottles! 
  • Avoid Root Rot: Allow your soil to dry out completely between watering/feeding. Use hydroton and perlite to promote drainage in your soil. Consider using airpots or fabric pots. Use an enzyme product (Enzymes Komplete, Hygrozyme), hydrogen peroxide, or Clear Rez to keep your root zone sparkling.

Notes: Consider treating fungus gnats as a two-part process: The adults that live above soil, and the larvae that lives in the soil. You need to kill both of them to solve the problem. Also, please be aware that they may live inside your drain, your recycling bin, or hide under the rim of your toilet. 

Cabbage Loopers

Identification: These bright green or turquoise inchworm-like caterpillars are typically found on the undersides of your leaves. They are well camouflaged. Leaves may appear weighted-down.
Control: Pyrethrins, insecticidal soap, yellow sticky traps, diatomaceous earth, hand-picking.
Biological Control: BTK
Notes: Caterpillars are typically only a problem on outdoor grows. They must be dealt with swiftly, as they can devour your entire crop in a matter of days. Plants such as lettuce, Swiss chard, cabbage and cauliflower are magnets for cabbage loopers. Kill any moths that enter your grow room.

Root Aphids

Identification:  Can cause curled or yellowed leaves and a failure to thrive. Can be white, orange or black. Some individuals have wings. Will be found in the root zone and above the soil line. Can affect both hydroponic and soil operations. Any ant activity around your stem is a danger sign, as ants will tend to the aphids. Adult root aphids produce a white, waxy secretion which can make them look like mealybugs.
Control: Pyrethrins, hydrogen peroxide (4:1 solution) discarding affected plants.
Biological Control: Nematodes. Ladybugs will eat the adults above ground.
Prevention: Do not reuse soil or pots unless they are thoroughly cleaned in hot, soapy water. Do not purchase soil from big box stores that store it outside.
Notes: Root aphids can be spread via water, can crawl out of affected plants, and their eggs can be transported and propagated by ants. 


Identification:  Non-moving or slow moving “bumps” on your plant. Males may appear as gnat-like flying insects. Ants may be present because they feed off of the secretions that scale insects create.
Control: Hand-picking, pruning, N-Force, 70% isopropyl alcohol applied directly to individuals, pyrethrins. Manual removal is most effective as they are protected by their waxy shells.
Biological Control: Ladybugs may eat the larvae, although they will have no effect on the armoured adults.


Identification:  Small, white, fluffy insects. Can be confused for root aphids or powdery mildew. You will see blobs of white fluff on the stems and leaf nodes. Damage causes the leaves to yellow and eventually drop from the plant. Ants may be found protecting and farming the mealybugs.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, water jets, 70% isopropyl alcohol applied directly to individuals, N-Force.
Prevention: Do not over-fertilize. Excessive nitrogen levels attract mealybugs.
Notes: Frequently found on and transmitted by cactuses and tropical houseplants such as hoyas. 

Powdery Mildew

Identification:  White, powdery spots or patches on the top side of leaves or on plant stems. New growth may appear twisted and stunted.
Control: Defender, 3-in-1, Milstop, evaporated sulphur, pruning, washing tent and room with hot, soapy water.
Prevention: Ensure your indoor garden has adequate ventilation. Avoid walking through areas with many weeds. Avoid replanting in areas where powdery mildew has been discovered, as it can persist year after year. Powdery mildew is often found in back alleys and along roads in Calgary. Pay attention to the plants where you’re walking, and don’t wear contaminated shoes into your garden! Cucumbers and other cucurbits should be monitored should you choose to grow them in your yard.

Leaf Miners

Identification: Can be identified by the shiny tunnels that they leave in your leaves.
Control: Squish them by squeezing the leaves. Pyrethrins. N-Force.
Notes: Since the larvae are hidden within the leaves, you must take an affected leaf from your plant and place it in a plastic bag. Monitor it daily. When the adults emerge as small black flies, it is time to begin spraying your plant. Plantains and poplar trees are common sources of infestations. 


Hemp Russet Mites

Identification: Hemp russet mites are nearly invisible to the eye, but can be seen as a yellowish mass once the infestation is advanced. In lower numbers, they unfortunately appear very similar to trichomes and leaf hairs. They cause leaf curling and top drooping. 

Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, water jets, N-Force, pruning infested portions and burning them.
Biological Control: Cucumeris, persimilis, stethorus, fallacis. Nematodes may eat the eggs in the soil.
Notes: Russet Mites have not yet become established in Alberta, but they are extremely widespread in places like California and Oregon. Please be extremely diligent if you have returned from the USA. Can be spread via fans indoors, and live inside of the plant. 

Mosquito Larvae

Identification:  Long, brown insects that flip around in the water and appear to “hang” from the surface.
Control: Empty your reservoir.
Biological Control: Mosquito dunks
Prevention: Air stones, fast-moving water, frequent reservoir changes, using a lid on your rez.
Notes: Mosquitos won’t harm your plants, but you still want to kill them. 


Identification: Small white flies on the underside of leaves.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, water jets, N-Force, low-powered vacuum cleaner.
Notes: White flies cannot survive the winter outdoors in Alberta, however they will overwinter indoors. Care must be taken to avoid harbouring these pests in your greenhouse or indoor garden. Poinsettias often carry whiteflies.

Broad Mites


Identification: You are unlikely to see the mites. Your plants will instead appear twisted and shiny.
Control: Pyrethrins, insecticidal soap, diatomaceous earth, yellow sticky strips, water jets, N-Force, pruning infested portions and burning them.
Biological Control: Cucumeris, persimilis, stethorus, fallacis. Nematodes may eat the eggs in the soil.



Identification: Tiny, wingless insects measuring about 1-3 millimeters in length. Come in both black and white. Can jump. Some species may be mistaken for worms.
Control: Improving drainage, adjusting watering practices, enhancing air circulation, removing organic debris, and using sticky traps to monitor their presence.
Prevention: Practice good sanitation, maintain balanced watering, quarantine new plants, and control ventilation and humidity levels. 
Notes: Springtails are generally harmless. They prefer to feed on decaying organic material, such as mold, fungi, algae, and plant debris. While heavy infestations indicate underlying issues, they rarely cause damage to cannabis plants themselves. 

Uses: Springtails are commonly used in bioactive gardening, where a diverse community of organisms, including beneficial insects, microorganisms, and decomposers, are introduced to create a self-sustaining ecosystem. In such setups, springtails play a valuable role in breaking down decaying organic matter, assisting in nutrient cycling, and promoting soil health. They feed on mold, fungi, algae, and plant debris, contributing to the decomposition process.

In vermicomposting, springtails can also be introduced as part of the composting ecosystem. They aid in the breakdown of organic material and help maintain a balanced microbial community, benefiting the overall composting process.

When introduced to a bioactive terrarium, springtails establish a self-sustaining population, working alongside other beneficial organisms to maintain a healthy and balanced ecosystem. 

Share this post