What term describes caterpillars that inject their venom through hollow body hairs?

The term that describes caterpillars that inject their venom through hollow body hairs is "urticating." Urticating hairs are specialized structures found on certain species that can deliver irritants or venom when they come into contact with skin. These hairs act somewhat like darts, helping the caterpillar defend itself from predators.

In contrast, "poisonous" typically refers to organisms that are harmful when ingested or touched but do not actively deliver their toxins. "Venomous" indicates an organism that actively injects venom through specialized structures, but in the context of caterpillars with hollow body hairs specifically, the correct term is urticating because it highlights the mechanism of delivery through those hairs. The term "invasive" is unrelated to the discussion of venom or toxins; it refers to species that are not native to an area and can disrupt local ecosystems.