Ask the Experts, Tree Care & Trimming

Gall Wasps in Dallas, Texas: Apple Oak Galls

October 27, 2023

In the heart of Dallas, Texas, you can often find evidence of gall wasps, a natural phenomenon that intrigues many residents. Gall wasps create oak apple galls that provide a unique and intriguing glimpse into the world of trees, insects, and ecology. To better understand these strange orbs, commonly found on oak trees, we’ve consulted with one of Southern Botanical‘s Certified Arborists for more information.

The Oak Apple Wasp: A Remarkable Insect

The oak apple wasp (Amphibolips confluenta) is a fascinating insect that plays a pivotal role in the creation of galls on oak trees. Galls are abnormal growths or structures that form on the leaves, stems, or branches of trees as a result of insect activity. The oak apple wasp, in particular, is known for its remarkable ability to manipulate the growth of oak trees to create a safe haven for its offspring.

We spoke with Steve Clary, an ISA Certified Arborist with extensive knowledge of local ecosystems, to gain insight into the relationship between oak apple wasps and oak trees in landscapes across Dallas, Texas.

STEVE CLARY

Steve is an award-winning arborist who specializes in risk management, inventory management, and plant healthcare strategies for urban forests. His keen understanding of the latest industry technology enables innovative approaches related to preserving tree assets with both value and sustainability in mind. 

Steve Clary, Certified Arborist, on Gall Wasps and Oak Apple Galls

“Oak apple wasps are truly remarkable creatures,” says Clary. “These small insects lay their eggs on the oak tree’s leaves, injecting a chemical into the plant that causes the formation of galls. The gall serves as a protective enclosure for the developing wasp larvae, shielding them from predators and providing a ready source of nutrition.”

Galls can vary in size and appearance, often resembling small, round apples. Hence, the name “oak apple.” While the appearance of these galls might be concerning to some tree enthusiasts, Clary reassures us that they are generally harmless to the overall health of oak trees.

“Oak apple galls are more of a cosmetic concern than a threat to the tree’s well-being,” Clary explains. “The wasp larvae inside the gall feed on the surrounding tissue, but the tree usually compensates for this loss, and the overall impact on the tree’s health is minimal.” Often, you can find galls on sidewalks, crushed by pedestrians.

Understanding the Life Cycle of Oak Apple Wasps

The life cycle of oak apple wasps is closely intertwined with the oak trees they inhabit. Adult wasps emerge from the galls in late spring or early fall, and females go on to lay eggs on young oak leaves. The cycle then repeats, with the newly formed galls providing shelter and sustenance for the next generation.

Clary advises, “If you notice oak apple galls on your trees, it’s generally best to leave them undisturbed. Nature has a remarkable way of balancing itself, and these galls play a vital role in local ecosystems by providing a food source for various wildlife, such as birds and small mammals.”

Appreciating the Role of Galls in Ecosystems

Galls are not unique to oak apple wasps and oak trees but are found on a wide range of plants and trees. These growths can be caused by various insects, mites, fungi, or bacteria. Understanding the role of galls in local ecosystems is essential for appreciating their significance.

“Gall wasps are a testament to the interconnectedness of nature,” says Clary. “Galls provide a safe environment for developing insects, contribute to nutrient cycling, and even support the overall biodiversity of the area. In many ways, they are a sign of a healthy ecosystem.”

Harmless Galls

The presence of oak apple wasps and galls in Dallas, Texas, is a testament to the intricate relationships that exist within our local ecosystems. These small, yet captivating insects play a crucial role in oak trees’ life cycles, while the galls they induce are harmless to the health of the tree.

As we’ve learned from certified arborist Steve Clary, while oak apple galls might be unsightly to some, they are generally harmless to the trees they inhabit and contribute to the rich tapestry of life in landscapes across Dallas, Texas. So, next time you come across one of these intriguing natural formations, take a moment to appreciate the intricate dance of nature that unfolds right in your own backyard.