Pecan trees are a staple of Texas landscapes and agriculture. But every July, they face a major threat from a pest called the Walnut Caterpillar. Over the years, I’ve seen firsthand how destructive these pests can be, and this past summer was no exception. We received dozens of calls from homeowners in neighborhoods and properties surrounding Houston Country Lake just above Crockett and up in Palestine, where caterpillars were swarming trees and threatening to wipe out pecan harvests.

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The good news? With the right approach, you can protect your pecan trees and enjoy a healthy crop. Let’s walk through how to spot these caterpillars, why they target pecans, and the most effective ways to stop them.

🐛 Understanding the Walnut Caterpillar

The Walnut Caterpillar is the larval stage of the Walnut Moth. These caterpillars can grow up to 2 inches long, changing appearance as they pass through five different molts (instars). They can look very different from week to week, which is why infestations often catch homeowners by surprise.

Walnut caterpillars aren’t picky. They attack Black Walnut, English Walnut, Japanese Walnut, Persian Walnut, Butternut, Hickory, and, of course, Pecan trees. Unfortunately, pecans are especially vulnerable because of how plentiful and widespread they are across East Texas.

🌿 Why They Attack Pecan Trees

Simply put — the leaves are food. Walnut caterpillars feed on pecan and other related trees during the summer months of June and July, when conditions are perfect for their growth.

If you’ve ever seen a tree under attack, you’ll know it immediately. Caterpillars cluster in huge groups, covering branches and devouring foliage. Once you’ve witnessed it, you’ll never forget the sight.

⚠️ Impact on Pecan Trees

The damage can be devastating. Caterpillars strip trees of leaves, leaving them weakened and stressed. This reduces nut production and, in severe cases, can cause complete defoliation — meaning the tree loses every single leaf.

For pecan growers, this is more than an eyesore; it’s lost income. For homeowners, it means weaker trees and fewer pecans come harvest season. Left unchecked, repeated infestations can even shorten the lifespan of your trees.

This summer alone, we saw multiple cases in Nacogdoches and Crockett where entire trees were nearly destroyed before homeowners called for help.

🛠️ Controlling Walnut Caterpillar Infestations

🔍 Monitoring and Early Detection

The best defense is catching them early. Inspect your pecan trees regularly in June and July for caterpillars or feeding damage.

🧴 Pesticide Control Methods

Insecticides can be effective, but you must use ones labeled for edible plants. The last thing you want is to contaminate your pecans. Always read labels carefully and follow directions to protect your crop and the environment.

👨‍🔧 Call in the Professionals

If you’re not sure what you’re dealing with, or if the infestation has gotten out of hand, professional help is the safest route. At Critter Gitters, we were able to save dozens of pecan trees this past summer by acting quickly and treating infestations before they spread.

✅ Final Thoughts

Walnut caterpillars are a serious and recurring threat to Texas pecan trees. But with regular monitoring, safe treatment, and, when needed, professional pest control, you can keep your trees healthy and productive.

Whether you’re a farmer or just enjoy the shade and harvest from the pecans in your backyard, don’t wait until caterpillars devastate your trees. Stay proactive, and you’ll protect your investment — and your pecan crop.

📚 Additional Resources

• NC State Extension –  local extension services for photos of different caterpillar stages.
• Your local pest control experts (like us at Critter Gitters) for hands-on help.