There is no such thing as a "white-tailed hornet." Hornets are typically characterized by their black and yellow markings.
Perhaps you're thinking of a different type of insect, or maybe you're describing a specific marking on a hornet. Can you tell me more about what you've seen?
For example:
- What was the size of the insect?
- Did it have any other distinctive features?
- Where did you see it?
With more information, I can help you identify the insect you saw.