The Primary Nest Foundation of Yellow Legged Hornets
In spring 2024, we had the opportunity to observe a Yellow-Legged Hornet (Vespa velutina) queen choosing her nesting site right on our premises.
Vespa Velutina Nest Development: 53 Days of Observation
What followed was a unique opportunity to document the complete early development of a hornet nest.
We could have removed it immediately, but doing so would have taught us very little. Instead, we chose to let her live. This gave us a rare opportunity to closely monitor her development, understand her early behavior, and identify both her strengths and vulnerabilities.
Tracking a Hornet Queen from Day 1
We installed a camera and recorded all her activity from the very first hours, over a period of 53 days. Using more than 20,000 images, we created a detailed record documenting each stage of yellow-legged hornet nest construction.
From the outset, we observed how the queen builds the initial stalk and comb, laying the first three to four eggs. We then witnessed how rapidly she constructs the first envelope, followed by the second, third, fourth, fifth, sixth, and seventh layers of the nest.
We also observed how she actively warms her eggs while simultaneously building the nest and foraging for construction material.
Time-Lapse of Vespa Velutina Nest Construction
At one point, we observed the queen confronting rival queens attempting to take over the nest. To ensure we were always studying the same individual—and not a replacement—we captured and marked the queen.
How to Estimate the Age of a Vespa Velutina Primary Nest
This documentation provides a valuable reference for estimating the age of a hornet nest based on its structure and number of envelopes. The table below summarizes these key stages.
| Photo | Day | Date | Stage | Future workers |
|---|---|---|---|---|
| 1 | March 19 | Building shell #1 | First eggs | |
| 7 | March 25 | Building shell #2 | Egg | |
| 15 | April 2 | Building shell #3 | Larva | |
| 27 | April 14 | Building shell #4 | Pupa | |
| 46 | May 3 | Building shell #5 | Workers are born | |
| 49 | May 6 | Building shell #6 | Workers are building | |
| 53 | May 10 | Building shell #7 | Workers are building |
Regardless of what one may think about this invasive species, it is difficult not to admire the capabilities nature has given it. Many details escape the naked eye, but through thousands of images, the full scale of the queen’s work becomes visible.
To effectively control an invasive species like Vespa velutina, we must first understand its behavior and lifecycle.