When you see little spider mites or their webs on any tree or plant, it’s never a good sign.
Not only do they damage Japanese maple trees, but they can lead to many diseases and fungal infections, which could stunt the tree’s growth and, in some cases, lead to its demise.
Despite their devastating effects on Japanese maples, spider mites can be removed with a strong stream of water. They also can be treated with horticultural soaps, natural insecticides such as neem oil sprays, or any of the available miticide products on the market.
To keep your Japanese maple healthy and free of spider mites, you’ll have to be vigilant and look for the first sign of a spider mite infestation.
It’s always easier to get rid of the little bugs early on than to let them build webs and multiply. Read more to find out how to deal with the spider mites on Japanese maple trees.
Are you ready for all the common pests and diseases that come with growing Japanese maples? Make sure you read my Japanese Maple Diseases and Pests guide.
Spider Mites on Japanese Maple
As with other pests, it’s always a good idea to look for the first signs of a spider mites infestation on the Japanese maple and to take immediate action. In many cases, this can prevent the bugs from damaging the tree.
To understand how best to get rid of mites, it’s important to know where they come from and how they reach the maple.
Where Do Spider Mites Come From?
Spider mites are close relatives of spiders. They have 8 legs and don’t have antennas. The female spider mites choose a dusty tree in a hot area to lay their eggs.
When the eggs hatch, the larvae start feeding on the leaves. The larvae turn into nymphs that keep feeding on the leaves until they turn into mature spider mites ready to procreate.
This whole phase takes about a week, which explains how a couple of spider mites on a maple tree can turn into an infestation within a short time.
How Do Spider Mites Spread?
Although spider mites don’t have wings and cannot fly, they’re usually so small that a strong gust of wind can carry them across long distances. They also spread through infected plants.
If you buy an infected plant from the nursery, the spider mites will jump to the trees and other plants in the garden and start to multiply. In other cases, spider mites will walk in search of a suitable tree to lay their eggs.
What Does a Spider Mite Infestation Look Like?
The first sign of a spider mite infestation is a few silver dots on the veins of the leaves, but a closer look will lead to more discoveries.
You’ll notice small white webs near the base of the leaf or on the undersides. The more webs you see, the more severe the spider mite infestation.
Then, you’ll see bronze discoloration on different parts of the tree. As the spider mites claim more territory, those bronze areas will move to the trunk.
How To Identify Spider Mites
Since spider mites are quite small and only grow to about 1/50 of an inch, identifying the pests with the naked eye is not easy.
However, you can tell that you have a spider mite infestation by looking for the telltale signs on the leaves and branches of the Japanese maple.
Look for white or yellowish specks on the top surface of the leaves. With time, these specks will merge into white spots on the leaf that cover the usual green color.
The white webs near the stem of the leaf or underneath it are another dead giveaway.
Spider Mite Damage
Spider mites during the different phases of their lives feed on the sap in the leaves of the tree. To get to that sap, they pierce the surface of the leaf with their mouths and suck the sap.
Since the sap is intended to feed the leaf, draining it causes the leaves to wilt. As more spider mites poke holes in the leaf, the discoloration spreads, and the leaf curls.
For an ornamental plant like the Japanese maple, this can be catastrophic. The whole canopy will look unsightly especially when the infestation is severe.
Add to that the bronze discoloration and the white webs that litter the foliage. Instead of adding to the landscape, the tree turns into a sore thumb that sticks out and begs to be removed.
When Your Trees Are Most at Risk
In general, spider mites thrive in hot and dry conditions. If you have dry summers, that’s when spider mites are more likely to strike.
The females like dusty places to lay their eggs, so an unattended tree will attract more spider mites than one that is well cared for.
Overfeeding can also make the tree a magnet for the pests by making the sap less bitter.
One other factor that makes your trees more prone to spider mite attacks is poor ventilation. An area dense in trees and vegetation creates the right conditions for spider mites to lay their eggs and spread.
How To Get Rid of Spider Mites on Japanese Maple
It’s not always easy to detect small pests like spider mites, let alone get rid of them.
By the time you have seen the telltale signs, the infestation might be too severe, and the Japanese maple will likely be struggling.
However, you can still get rid of the pests no matter how severe the infestation using one or more of the following solutions.
Training the garden hose at high velocity toward the branches of your Japanese maple will dislodge the pests as well the eggs, larvae, nymphs, and all other stages of the spider mite’s life.
The downside to this method is that you might not be able to reach the pests at the top of the tree. There’s also a chance that they would crawl back up the tree again.
Spider mites have natural enemies. These are predator pests that feed on the mites without causing any harm to the tree.
Ladybugs, lacewings, and predatory mites do a good job of eliminating low-level to medium-level spider mite infestations. Once they’ve fed on the last spider mite, they usually move out of the tree.
Horticultural Oils & Soaps
Insecticidal soaps and horticultural oils such as neem oil (I use this organic neem) are effective ways to combat severe infestations.
In many cases, you’ll need more than one application to get rid of all the spider mites on the Japanese maple.
Spray the oil once every 3 to 5 days in the spring or fall to kill the eggs before they hatch.
The best time to apply horticultural oils and soaps is in the early morning before the temperature exceeds 90 degrees Fahrenheit.
Special products designed specifically to target mites are another option. Bioadvanced makes a great one, but as long the label mentions mites, you’re good to go.
Homemade Spider Mite Killer
If you see the first signs of a spider mite infestation on your Japanese maple and you don’t have any of the above methods readily available at home, you can rustle up your own homemade spider mite killer and use it effectively against the little pests.
You’ll need 70% rubbing alcohol and dish soap.
Mix 1 cup of alcohol with 30 ounces of water. Add a few drops of dish soap, and mix well.
Fill a spray bottle with the solution, and apply it to the infected parts of the Japanese maple. Spray again every 3 days until you have eliminated all the pests.
How To Prevent Spider Mites
- Sterilize all your gardening tools before and after using them or lending them to a neighbor.
- Make your own plant cuttings using sterilized tools.
- Improve ventilation around the trees and plants in the garden.
- Spray plants you buy from the nursery or online with neem oil before planting them.
- Check your plants and trees regularly, especially during the summer, for signs of infestation.
Do Spider Mites Make Webs?
Spider mites are distant cousins of spiders. They have 8 legs and don’t have antennas. They make webs near the base of the leaves and around the stems. The webs are small and silvery white.
Do Spider Mites Kill Plants?
Heavy spider mite infestation can indeed kill a plant, especially if the plant was already in a weakened state. However, if the infestation is detected and treated early, full recovery is likely.
Spider mites can cause a lot of damage to an ornamental tree like the Japanese maple.
Check for signs of infestation regularly, and apply neem oil or horticultural oil, or make your own spider mite killer at home from rubbing alcohol and dish soap.
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