Spider Mites, Aphids and Thrips, Oh My! Common Cannabis Pests

Spider Mites, Aphids and Thrips, Oh My! Common Cannabis Pests

Common Cannabis Pests

It can be common for new growers to experience pests when growing cannabis. These common pests with cannabis can, in many cases, be prevented by keeping an ideal environment. Common pests when you’re growing cannabis include spider mites, aphids, thrips and fungus gnats. So, let me help you learn about how to identify them, how to prevent them and get rid of them.

Spider Mites

Two Spotted Spider Mite

Identifying Spider Mites

Spider mites are very tiny mites who get they name because of the webs they create. Their small size can let infestations get quite large before the grower notices, which can make them harder to get rid. You’ll usually find them on the underside of leaves. But, you’ll need a jeweler’s loupe, digital microscope or magnifying lens. In fact, it can be very difficult to spot spider mites with your naked eye. 

You’ll notice little spots on leaves. They can appear to be yellow, brown or orange. Eventually they can cause yellowing or browning of leaves. As a result, the leaves fall off prematurely. If the infestation goes on for a long time, unnoticed, you’ll start seeing their webbing on the plant. They can reproduce very quickly and an infestation can ruin a crop rather quickly. It’s vital to find them early on if you want to save your crop.

Preventing Spider Mites

Spider mites cannot reproduce in windy conditions, so having proper air circulation is important in prevention. For this reason, it’s a good idea to have a fan or fans oscillating around the room. It’s also a good idea to keep the temperature from getting too high. For more about The Importance of Proper Air Circulation, click the link.

You can also prevent infestations by avoiding going from outdoors (especially in gardens and other cannabis grows) directly into your grow room. You don’t want to bring any plants from outside into your grow room without treating them first. This helps to reduce chances of bringing anything into your grow area. It’s good to regularly check your leaves for anything deficiencies or pests. This can help you catch an infestation earlier.

Getting Rid of Spider Mites

It can be very tricky to get rid of spider mites because they can quickly become resistant to treatment. So, you’ll have to be persistent. For this reason, It can be beneficial to use multiple methods of treatment. Some solutions for spider mites include neem oil, alcohol, diatomaceous earth, lady bugs and other predatory mites.

Neem Oil

Neem oil is natural oil which can be used for spider mites in vegetation and early flower. You’ll need a mister to spray the plant evenly. Spray the underside of the leaves thoroughly during lights out and then make sure to have a breeze on them to help them dry before lights on. If not, the plants will burn. The oil doesn’t smell very good, so avoid spraying on buds. You should spray plants every 3 days because most insecticides don’t kill the eggs and 3 days is how long it takes the eggs to hatch. So, repeating the treatment a few times will help ensure you get them all.

There is some evidence that suggests neem oil can be harmful to humans so I’d recommend wearing gloves and even a mask while spraying.

Alcohol & Water

You can also use alcohol and water to spray your plants. Use 9 parts water and 1 part alcohol. This will kill the spider mites without causing harm to the plants. Using a mister, spray the underside of leaves during lights out. Allow the plant to dry with fans before the lights come back on. You can apply every 3 days to kill the newly hatched spider mites.

Diatomaceous Earth

You can also add diatomaceous earth to the top of the soil. This solution is harmless to humans, pets and plants. It’s very sharp on a microscopic level and will tear or dehydrate spider mites on contact. This will not get rid of the spider mites by itself but is good to use in combination with other methods to help slow down the infestation.

Predatory insects

You can also add lady bugs or predatory mites to help control spider mites in your grow room. This can be a good option if it’s a small infestation or if you’re in flower and don’t want to spray your plants. They are natural pest control, but can be effects by other insecticides so always check the insecticides before using them if you’re using predatory bugs in your grow.

For predatory bugs in Canada, try http://www.thebuglady.ca


Two Aphids at Different Stages

Identifying Aphids

Aphids are small insects that can be green, yellow, white, brown, black and red. The adults are bigger and round or oval shaped. Where as, the nymphs are white, smaller and thinner looking. The nymphs can also be confused with thrips, so using magnification is recommended before any treatments. The adults can also be winged. These are called colonizer aphids because they fly off to start a colony on plants. The winged version still has the same body shape. They will most commonly be found on the underside of leaves and on stems. An infestation can get out of control in just a few weeks. So, again, early detection is key.

Preventing Aphids

You can prevent aphids in your indoor grow by avoiding going from outdoors (especially in the garden) directly to your grow room. This will reduce chances of bringing many common pests with cannabis into your grow. You can also add lady bugs, lady beetles or lace wings to your grow room to help prevent aphids from colonizing your plant. In fact, lady bugs can eat a large number of aphids. They won’t be able to get rid of aphids completely so they’re better used as a preventative measure, rather than a treatment.

Getting Rid of Aphids

When treating your plant for aphids, you want to try to get the numbers down quickly. Many common pests with cannabis can be treated by spraying your plants during lights out with insecticidal soap or neem oil.

Insecticidal Soap

Insecticidal soap or fatty acid salts can be very effective with treating aphids. They weaken the outer shell of the aphids, while being harmless to plants. They need to be reapplied because they only stay on the plant for a short time. It’s important to get good coverage when spraying with the soap. Even though it’s considered safe, avoid applying it on your buds. No one wants soapy buds. You’ll need to spray with this every few days to bring down numbers.

Neem Oil

Neem oil is natural oil which can be used for aphids in vegetation and early flower. You’ll need a mister to spray the plant evenly. Spray the underside of the leaves thoroughly during lights out and then make sure to have a breeze on them to help them dry before lights on. Otherwise, they will burn. The oil doesn’t smell very good, so avoid spraying on buds.


A Younger Adult Thrip

Identifying Thrips

Thrips look slightly different during different stages of their life. The nymphs look like white worms that don’t move. Where as, an adult thrip is a yellow, golden, transparent or brown bug that is fast moving. Thrips can also have wings depending on which stage of life they’re in. They can be found on leaves both underside and on top.

Thrips cause leaf damage that is similar to spider mites. But, the thrips spots are bigger and irregularly shaped. The spots also appear to be shiny, slimy, or silvery or bronze. The appearance has been compared to snail trails, where it’s shiny looking. If untreated, the leaves that were effected will start to die.

Preventing Thrips

You can help to prevent thrips by avoiding going directly into your grow room from outside, especially in the garden. This will reduce your chances of bringing pests into your grow.

Getting Rid of Thrips

You can get rid of thrips by spraying plants with insecticidal soap or neem oil. It is best to use these sprays during vegetation or early flower. You can use them in flower but you want to avoid spraying the buds.

You can also use predatory mites Stratiolaelaps (Hypoaspis) to help control thrips. They can be added to the soil and will eat up the thrip pupae. This will prevent them from reaching adulthood and laying more eggs.

Fungus Gnats

An Adult Fungus Gnat

Identifying Fungus Gnats

Fungus gnats are tiny little flying bugs. They live in the soil or medium and lay eggs in the top few inches of growing medium. They’re most commonly found in soil. They will fly right near your face when you’re in your grow room working on plants.

Preventing Fungus Gnats

You can prevent fungus gnats by using quality soil and avoid using regular garden soil. These often times have fungus gnat larva in the soil. You can also prevent fungus gnats by letting the top soil dry out between watering. In order for them to thrive, they need wet soil. You can also add a top layer of sand as this dries out faster than soil.

Getting Rid of Fungus Gnats

You can get rid of fungus gnats you can use a mixture of hydrogen peroxide and water to oxygenate the soil. This will kill larvae on contact. You can also sprinkle cinnamon on the soil to kill the fungus in the soil that the larvae are feeding on.

You can also use predatory mites, Stratiolaelaps (Hypoaspis), to control fungus gnats. These mites eat the larvae in the soil. Therefore, preventing further fungus gnats from reaching adulthood and laying more eggs. 

To learn more about how to Get Rid of Fungus Gnats For Good! Click the link.

Cleaning Grow Room After Common Cannabis Pests 

After an infestation of ANY of the common pests with cannabis, you will need to thoroughly clean and disinfect your grow room. It is best to use a bleach and water mixture. For a more natural method, clean the dirt and dust with a solution of vinegar, water and soap. Follow up by wiping down surfaces with hydrogen peroxide. You’ll also need to clean your pots with the same solutions. Make sure to rinse well and allow to dry before using again.

For 5 Grow room cleaning tips for healthier plants, follow the link.

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