Gall Making Insects and Mites: Identification and Control Guide

Plants can develop unusual growths called galls, often caused by gall-making insects and mites. These pests create protective structures on leaves and stems where they feed and grow, leading to visible damage and changes in plant appearance.

Gall Making Insects and Mites

Plants can see abnormal growths called galls due to bacteria, insects, fungi, mites, and other organisms. When it comes to insects and mites, there is usually a gall maker, providing a steady food source within the gall, allowing the gall maker to house itself and remain safe.

You’ll usually find that galls are only on one plant species at a time, and they are created by a specific species of mite or insect. Gall-making insects and mites are common in Colorado, especially during the late spring growing season when trees are most vulnerable.

How Are Galls Formed?

Galls are due to the thickening of the leaf tissues. They can also form due to the stunting of the tissues’ growth. These are called indeterminate galls.

You can also find insects and mites can cause the structure of the original tissues to form unexpectedly. These are known as determinate galls.

Why Galls Are Problematic for Plants

The galls will create issues for trees and plants due to the way the water and food transportation is affected. You may not see any other injury to the plant at first, but the galls can lead to blockages, preventing the food and water getting to all areas of the plant.

Once the galls have formed, they can’t be removed. In fact, it’s not even worth trying to stop the formation once started in the majority of cases. While there is some damage to the plants, that damage isn’t going to affect the health of the plants in a large way. You end up with an unsightly look, though.

Tackling the Problem of Gall Making Insects and Mites

The good news is that the majority of galls are formed during the rapid growth period. This is usually in the late spring, and you can tackle the problem before it becomes an issue. The best way to do that is to get rid of the mites and insects before they hatch from their eggs.

It is possible to control some of the insects and mites when they overwinter. You’ll want to add a dormant oil to the trees. You will also need to lay insecticide over the leaves during the egg laying period, but this is something you’ll need to do a couple of times in the earlier season to see good results.

Frequently Asked Questions

What causes galls on plants?
Galls are caused by insects, mites, bacteria, or fungi that trigger abnormal plant growth.

Are galls harmful to plants?
Most galls are more cosmetic than harmful, though heavy infestations can affect plant growth.

Can you remove galls once they form?
No, once galls form they cannot be removed, but future infestations can be prevented.

When should you treat gall insects and mites?
Treatment is most effective in early spring before eggs hatch.

If you’re seeing unusual growths or galls on your trees, SprayTech can help identify the cause and prevent further damage. Our team provides targeted treatments to manage gall-making insects and mites before they spread. Call SprayTech at 720-248-0000 to protect your trees and landscape.