Spider mites are tiny arachnids that attack and kill plants and trees if they aren’t stopped. So how can you tell if a plant has spider mites?
A plant or tree with spider mites has webs that are thicker than a spider’s between its leaves, stem, and/or branches. Over time, its leaves turn yellow, wilt, and fall off near the webbing. As the spider mite infestation expands, the plant stops growing and eventually dies.
Spider mites are so small that they can be difficult to see with the naked eye, but they leave big clues they are the ones killing your plants. The problem is that many people mistake spider mite damage for something else, like too much sunshine or water, because all of these threats look very much the same in plants. You need to know all 9 signs below to be sure.
In this article, we’ll cover:
- The 9 signs that a plant has spider mites
- How to get rid of spider mites
Your plant might have spider mites if it has …
Thick webbing on the leaves, stem, and/or branches
Spider mites got their name because they build webs, much like spiders. But there are some key differences between a typical spider web and spider mite web (there are many types of spiders and spider mites so it’s not possible to cover all the variations here today).
The table below provides a list of how to tell the difference between a spider’s web and a web made by spider mites:
|TRAITS OF A SPIDER WEB
|TRAITS OF A SPIDER MITE WEB
|A spider’s web is usually flat and one-dimensional, with clear circles getting bigger and bigger as they move out from the center of the web.
|Spider mites build a much thicker web that has many strands running in all directions.
|A spider’s web may be attached to a plant’s leaves, stem, and/or branches, but the body of the web is usually out in the open air so it has the best chance to catch insects passing by.
|Spider mites build webs only to protect the mites and their eggs, so a spider mite web is constructed very close to the infested plant. These webs are often wrapped from one side of a leaf to its other side, and may make the leaf start curling in on itself.
|If you look closely, a spider’s web usually has one spider in it, and the spider is large enough to see quite easily when you’re looking for it.
|If you look closely, a spider mite web has many tiny spider mites crawling around in it. Spider mites are most commonly red, but they can also be brown, yellow, or green.
|You might see insects caught in a spider’s web. If an insect has been there long enough and looks tasty, it will be wrapped in silky strands by the spider as it waits to be eaten.
|Spider mites eat plant sap, not insects. So while a random insect might get stuck in the web here and there, insects are not eaten or wrapped up by spider mites for later.
Be sure to look for spider mite webs:
- On top of and under leaves
- Between the leaves at the end of a branch
- Where leaves join the plant’s stem or the tree’s branches
The more spider mites that are present, the more webbing there will be. The plant in the photo below is suffering from a very serious spider mite infestation:
There are specks of “dirt” on the leaves
Spider mites and their eggs often look like dust or specks of dirt to the naked eye. If you see what looks like dust on the top or bottom of a plant’s leaves, you might have spider mites.
To test if you are seeing dust or spider mites, take a white sheet of paper and hold it under the leaf. Shake the leaf or scrape it gently so the specks fall onto the paper.
Now take a closer look with your own eyes or a 10X magnifying glass, like this handy little one from Amazon.
You should be able to tell if you are looking at live spider mites or regular dirt.
There are white dots on the leaves
Spider mites love to eat the juices in leaves. To get to these juices, spider mites pierce leaves with their mouth and suck out the sweet sap inside.
Each time a spider mite pierces a leaf to eat, it makes a hole about the size of a pinprick. Each of these holes looks like a white or silver dot on the leaf, which is a sign that you can look for.
It’s easy to confuse these white dots for aphids, another plant killer. Click here to find out how to tell the difference between a spider mite infestation and an aphid infestation.
If you suspect a plant has spider mites and you look closely at its leaves, you’ll notice many small holes or white dots where the mites have been feasting. Spider mites tend to bite a leaf many times in the same area, so there are usually many holes in a cluster close together.
The leaves have yellow or brown spots
Sap is fluid found in a plant’s leaves. It carries food, waste, and other essential nutrients around the plant. It’s also what makes a plant’s leaves firm enough to hold its shape.
Spider mites eat plant sap. When they suck too much sap out of a leaf, the leaf’s tissue in that area collapses and turns brown or yellow. At first, you will notice brown or yellow blotches on the leaf.
As the spider mite infestation gets worse and they continue sucking out the sap, the spots on the leaf get bigger. Eventually, the entire leaf goes from green to a sickly yellow or brown.
It’s easy to confuse brown, limp leaves with sunburn or overwatering. If your plant has yellowing leaves, check it over for mites.
There are droopy or wilting leaves
A leaf’s pores are called stomata. Stomata make it possible for a leaf to maintain a balance between the water inside the leaf and the air around it.
When spider mites live on a leaf, they cause a lot of damage. Studies show that the leaf will keep its pores open for longer if there are spider mites living on it, which makes the leaf lose a lot more water than it should (source).
Also, spider mites build thick webs around a leaf that weigh it down and make the leaf curl inward.
Over time, the water loss and webbing make the leaf limp, until it droops and no longer points up as it did before.
The plant stops growing
When a plant is badly infested with spider mites, it stops growing.
Spider mites drink the plant’s sap, which carries essential nutrients around the plant. This liquid food feeds the plant so it stays alive and grows. When too much sap is removed, the plant becomes malnourished and cannot develop any further.
If your plant doesn’t want to grow, especially if nearby plants seem healthy and thriving, then spider mites might be the culprit.
The leaves start falling off
If a plant’s leaf turns yellow and wilts, it is showing signs of weakness. If spider mites keep on attacking it, the leaf shrivels up and drops off.
When a plant loses too many leaves it can’t use sunshine to make food. The plant slowly wastes away and dies.
There are spider mite signs in one section
Spider mites usually attack one part of a plant first, then move along as the leaves in that area turn yellow, die, and fall off. They move around to find fresh plant material to eat.
Spider mites live on the plant or tree, not in the soil below it. If you see tiny organisms moving around in the soil below your plant, you might have soil mites or root aphids. Click here to find out how to tell the difference between the two.
Spider mites often choose a warm spot on the plant to start with. Say your plant is in a greenhouse, then spider mites will most likely be found on the bottom of the leaves that are closest to the glass, where the daylight sun’s heat can be felt most.
If you notice several signs of spider mites in one section of a plant, and this damage seems to move from one leaf to the next over time, there’s a good chance you have spider mites.
You get itchy around the infested plant
Spider mites are tiny and pretty harmless, and they don’t have many ways to protect themselves from threats. But spider mites still try to protect themselves by releasing a substance that can irritate skin, though this usually only has an effect on people with a sensitive skin.
If you itch every time you work with or walk past a certain plant, take a closer look to see if you have any visitors.
How to get rid of spider mites
Below is a carefully selected list of the best products from Amazon and recommended methods to get rid of spider mites in your yard:
- As soon as you see any of the above signs of a spider mite infestation, especially if you see the spider mites with a 10X magnifying glass, wash the plant with warm, soapy water. Click here for a recipe using dish soap that you probably already have in your home.
- If the infestation is very bad, put a plastic bag over the infested area. Cut off the infested branch close to the stem, making sure you don’t shake the mites out of the plastic bag. Spray the infested branch in the bag with a miticide, such as this one from Amazon. Seal the bag and throw it away.
- If the spider mite infestation isn’t too bad, spray the spider mites directly with a good miticide like this one. You must use a miticide to kill spider mites – an insecticide spray won’t work – and the product needs to come into contact with the mites to kill them.
- If you need an organic spider mite killer or you want to kill spider mites indoors, try this peppermint plant-based spray that’s safe to use around people and pets. The brand prides itself on being made from plants for plants.