Red Spider Mite Insecticides: Get These Pests Before They Kill Your Plants!

Also known as the two-spotted spider mite, the red spider mite (Tetranychus urticae), is one of the most common species of this pest. It feeds on more than 200+ species of plants, including marijuana. The worst thing is that these mites can damage or kill your plants at breathtaking speed.

Below, I highlight what red spider mites are, why you need to get rid of them as soon as possible, and the types of insecticides you can use.

What Is the Red Spider Mite?

It is one of over 1,200 species of mite and is believed to be one of the most harmful pests for agriculture. Red spider mites are about 0.5mm long and are difficult to spot, not just because of their size but also due to their tendency to hide beneath leaves.

They are occasionally confused with spiders because of their ability to spin webs, which they use to trap natural predators. What’s also problematic is that these webs can protect red spider mites from some pesticides known as acaricides.


These pests are less of an issue outdoors because they die off during the winter when the temperature drops. Typically, red spider mites die at temperatures below 32 degrees Fahrenheit and struggle to develop below 50 degrees. On the other end of the temperature scale, these mites may die once temperatures exceed 104 degrees.

As such, red spider mites not only survive within the temperature range of an indoor marijuana grow, but they thrive. Therefore, the rise in indoor cannabis cultivation means that this particular pest is becoming a real problem.

Why Are Red Spider Mite Infestations So Bad?

First and foremost, this pest causes tremendous damage to marijuana plants. In fact, a serious red spider mite infestation could kill a plant overnight! They feed on your plants’ sap, which results in the leaves turning yellow and drying out.

Red spider mites also produce thick cobwebs that cover plant branches and leaves. Consequently, the processes of transpiration and photosynthesis are greatly affected. Additionally, this mite can transmit viruses to your plants, ensuring that they become weaker and more vulnerable to other pest infestations.

Even if your plants survive the attack, they become heavily stressed and will lose leaves. Their growth will slow, and at harvest, your plants will be smaller and produce lower yields. If that isn’t bad enough, the damage caused by the mites will negatively impact the taste of the buds.

Red Spider Mites Are Prolific Breeders

This pest lays its eggs on the underside of the leaves, making them hard to spot. A single red spider mite can lay approximately 100 to 150 eggs during its life cycle, or around five to ten a day. After being laid, the eggs will hatch two to seven days later.

Furthermore, an adult red spider mite can live for up to 30 days. So, it doesn’t take long for an infestation to get out of control and weaken the natural defenses of your marijuana crop. If your plants are located close together within the indoor growing room, these mites can easily spread.

For the record, red spider mites are most prevalent in the spring and summer. If you see spots with an intense red or greenish-brown color on your plants, it could be a sign of an infestation. They can appear on both sides of the leaves, and if you view your plants for long enough, you’ll likely witness the slow movement of these dots.

However, grey or small white dots could also be a sign of red spider mites, as they leave these colors on leaves when they feed. If you have a magnifying glass or microscope, it becomes very easy to spot these pests.

Getting Rid of Red Spider Mites: What Insecticides to Use

Unfortunately, this pest is quite tough to eliminate. They have a nasty tendency to survive after you think they’ve been defeated. Many farmers have breathed a sigh of relief, only to find that the red spider mites return with a vengeance after a few days or even a few weeks!

Also, they are highly resistant to sprays and can become immune to whatever you use to kill them at astonishing speed. Thus, if you don’t destroy the entire infestation at once, you’ll end up with a group of mites that have developed a powerful tolerance to certain insecticides and pesticides.


There are three types of insecticide you can use. Let’s briefly analyze all three below.


There are plenty of miticides and acaricides on the market that are designed to kill red spider mites. The problem with products of this nature is that they also eliminate insects that prey on the mites. Thus, you inadvertently increase the chances of red spider mites surviving. Add in the fact that these mites can quickly develop resistance to these chemicals, and you have a disaster on your hands.

Also, the vast majority of miticides don’t affect eggs, which means you’ll need to reapply the chemical insecticide at a 10–14-day interval. Add in what it does to the quality of the cannabis, and this is a bad option.


A biological insecticide contains natural predators or microorganisms that control red spider mite infestations. Examples of such insects include the Stethorus species of dark-colored lady beetles and the Geocoris species of big-eyed bugs.

There are plenty of mites in the Phytoseiidae family known to be red spider mite predators. It’s even possible to order the likes of Neoseiulus californicus online. However, when considering predatory insects, you have to take into account how they will survive in your grow room. For example, certain predatory mites need a high level of humidity to survive.

It’s also essential to ensure that the insects you introduce to your cannabis garden are not harmful to your plants.


If you’re in the market for an organic insecticide, there are a few options. Such products contain natural ingredients, including plant extracts, essential oils, or insecticidal soaps.

One option is to mix an organic wetting agent with pure neem oil. Apply it to your cannabis plants every 3–5 days to destroy red spider mite eggs. What you need to do is spray all parts of the plant, including the undersides of the leaves. It’s best if you apply this solution at least six hours before you plan to switch the grow lights on.

A quick and easy way to reduce the risk of a red spider mite infestation is to water your plants regularly. This pest thrives in dry air, so increasing the moisture level can help keep them under control. Additionally, a forceful blast of water can remove and kill the mites residing on your plants. This process also gets rid of dust on the leaves, which could interfere with the progress of predatory mites.

Be Vigilant & Tackle Red Spider Mites Before It’s Too Late!

Although there are three main red spider mite insecticide options, it’s best to avoid chemicals if at all possible. Instead, consider using predatory insects or an organic mixture to deal with this pest.

Check your marijuana garden regularly to ensure red spider mites have not made an appearance. If you spot them, it’s essential to act fast. Otherwise, all your hard work could go to waste.

Plant Protection
Join The Discussion

By clicking "Post Comment” you agree with our Terms of Use and Privacy Policy

TOC Protection Status © 2000 - 2024 All Rights Reserved Digital Millennium Copyright Act Services Ltd. |

WayofLeaf use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it. More Information