Horntail wasps, also known as woodwasps, are large insects that can cause alarm due to their size and unique appearance. This article will clarify whether horntail wasps are dangerous to humans and provide information about their characteristics and behavior.
What Horntail Wasps Look Like
Horntail wasps are large insects, with some species reaching up to 4 cm (1.6 inches) long, and the pigeon horntail (Tremex columba) can grow up to 5 cm (2.0 inches) long, not including the ovipositor. Their bodies are cylindrical and lack the narrow waist seen in many other wasp species. Coloration varies by species, often appearing black, brown, or metallic blue, sometimes with yellow, orange, or rust-colored markings.
A distinctive feature present in both sexes is a stout, spine-like structure at the end of their abdomen, which gives them their common name “horntail.” Female horntails also possess a long, needle-like appendage called an ovipositor, which extends from beneath the abdomen. While these features might appear intimidating, they are key identifiers for these insects.
Are Horntail Wasps Harmful to Humans?
Horntail wasps are not dangerous to humans. They do not possess a functional stinger for defense and are not aggressive. The prominent “horn” at the end of their abdomen is not a stinger but a part of their anatomy.
The long, needle-like structure found on females is an ovipositor, an egg-laying organ used for drilling into wood to deposit eggs. This structure is designed for penetrating wood, not for stinging or injecting venom into humans. If a horntail wasp is mishandled, any “prick” felt would be from the mechanical action of the ovipositor, which is not venomous. They will not sting unless directly provoked.
Horntail Behavior and Encounter Guidelines
Horntail wasps are primarily wood-boring insects. Females lay their eggs within dead or dying trees. The larvae hatch and tunnel through the wood, feeding on it, sometimes for up to two years. Female horntails often introduce a symbiotic fungus into the wood when laying eggs, which helps break down the wood and makes it more nutritious for the developing larvae.
These insects are non-aggressive towards humans. If a horntail wasp is encountered, simply leave it alone. There is no need to try and catch or handle them, as they pose no threat. Horntail wasps play a role in forest ecosystems by contributing to the decomposition of wood.