Holes in Black Alder Leaves: Reasons and Solutions

Do you have a black alder tree on your property? If so, you may have noticed that the leaves are starting to develop holes. This can be alarming, but don’t worry – we’re here to help! In this blog post, we will discuss the causes of these holes and how to fix them. Keep reading for more information!

Why Are There Holes in My Black Alder Leaves?

The alder leaf beetle is usually the culprit behind holes in black alder leaves. These are small, black beetles that are known to feed on alder leaves. The good news is that they generally don’t cause long-term damage to the tree. However, if you notice that the leaves are being skeletonized (completely eaten), then you may need to take action.

While black alder beetles are usually to blame, there are many other pests that like to feast on alder leaves. These include the alder sawfly, aphids, and caterpillars. If you’re not sure what’s causing the holes, it’s best to contact a professional for help.

Try to catch the pests in the act by inspecting the leaves at different times of the day and night. This will help you identify what type of pest is responsible. If you see small, black beetles, then you know you’re dealing with alder leaf beetles. If you see small, green caterpillars, then you may have an infestation of sawflies.

How to Treat Black Alder Leaves with Holes?

It’s important to treat a black alder tree that has holes in its leaves as soon as possible. The longer you wait, the more damage the pests will do. However, once black alder beetles are present, it can be hard to get rid of them completely.

The first step is to manually pick off any beetles, caterpillars, or other pests that you see. This won’t get rid of all of them, but it will help reduce the population.

Next, you’ll need to treat the tree with an insecticide. Be sure to choose a product that is specifically designed for black alder trees and that is labeled as safe for use.

I’ve had good success with neem oil, which is a natural insecticide that is made from the neem tree. You can find this product at most garden stores. It’s a natural way to get rid of pests and it won’t harm the tree.

To use neem oil, mix it with water according to the directions on the bottle and then spray it onto the leaves of the black alder tree. Be sure to get both the top and bottom of the leaves. The

Once you’ve treated the tree, be sure to keep an eye on it and inspect the leaves regularly. If you see any new holes, then you’ll know that more pests are present and you’ll need to treat the tree again.

black alder beetle
Black alder beetle

How to Keep Pests Away From Black Alder Leaves?

It’s important to keep the beetles away from the black alder tree in the first place. The best way to do this is to promote beneficial predators in your yard, such as ladybugs. These helpful insects will feed on the alder leaf beetles and help keep their population under control.

You can also encourage more wildlife, like birds, to visit your yard. Birds are known to eat alder leaf beetles and other pests. So, if you have more birds around, they will help keep the pests away from your black alder tree.

Closely monitor your tree for any signs of pests and take action as soon as you see them. The sooner you treat the problem, the better chance you have of getting rid of the pests for good.

Finally, keep your garden clean and clear of debris. This means raking up leaves and removing any dead branches. A clean garden is less attractive to pests and will help keep them away from your black alder tree.

What Else Causes Holes in Black Alder Leaves?

There are a few other reasons why your black alder leaves may have holes:


Birds, deer, rabbits, and other animals may occasionally nibble on black alder leaves. This usually isn’t a problem, but if you see that the leaves are being eaten regularly, then you’ll need to take action to keep the animals away.

Distract them with food sources, such as bird feeders, or put up a fence to keep them out of your garden.


Sometimes, holes in black alder leaves are caused by disease. This is usually due to fungal infections, like powdery mildew. These can be difficult to treat and often require the use of fungicides.

If you suspect that your black alder tree has a disease, then take a sample of the leaves to your local nursery or garden center. They will be able to identify the problem and recommend a treatment.

The best way to prevent diseases is to keep your black alder tree healthy. This means watering it regularly, keeping the garden tidy, using fertilizer, and avoiding stress. Fungicide can be used to treat existing problems, but it’s always better to prevent disease in the first place.


Sometimes, holes in black alder leaves are caused by weather conditions, such as wind or hail. These usually aren’t a problem and will heal on their own.

If the damage is severe, then you can try to protect your tree from the weather. For example, you can put up a fence to shield it from strong winds. Or, you can cover it with a tarp during a hail storm.

Should I Prune Black Alder Leaves with Holes?

There’s usually no need to prune black alder leaves with holes. The tree will eventually shed the damaged leaves and grow new ones.

However, if the damage is severe, then you may want to remove the affected leaves. This will help the tree to focus its energy on growing new, healthy leaves.

To remove damaged leaves, use sharp pruning shears to cut them off at the base. Be sure to disinfect the shears before and after use to prevent the spread of disease.

After you’ve removed the damaged leaves, dispose of them properly. Don’t leave them in your garden where they can rot and spread disease. Instead, put them in a bag and throw them away.


The black alder beetle is the most common cause of holes in black alder leaves. However, there are a few other possible causes, such as animals, disease, and weather conditions.

If you see holes in your black alder leaves, closely monitor the tree and take action as soon as you see signs of pests. The sooner you treat the problem, the better chance you have of getting rid of the pests for good.

I hope this article was helpful. If you have any further questions, please don’t hesitate to ask. Thank you for reading!

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