As there is always the chance of a false positive, I thought it would be a good idea to keep the images whenever a hornet was detected, so they can be reviewed by a person.
I found a few articles on how to use MQTT to receive image data into Node Red, and on how to send image data via MQTT in Python.
Unfortunately, the Nicla Vision board hangs every time I try to send an image. It might be happening when it compresses the image to a smaller JPG for sending, or maybe when encoding the image data into a base64 string to be sent.
So I gave up on the real-time displaying of the image, and just settled on saving all of the hornet images onto the Nicla Vision built-in storage. It doesn't have much storage, but each image is only about 5kb, so on the 15MB it reports as having free right now, that's nearly 3,000 images. Hopefully we won't see any swarms of murder hornets that big! I guess then we'd have bigger problems!
As we already have the image there when the detection is made, this part was easy - just save the image. I added a counter so that multiple images can be saved. The counter resets when the board is reset, but for the intended use that should be fine.
Here is the result of some testing with our gnome standing in as the bad guy...
It's kind of cool that the ID circles are included in the saved pictures 
So then, in real life... if a message shows up on the browser that says a murder hornet was detected, someone would have to go to the installed Nicla Vision Bee Detector to grab and inspect the image files. A bit of an inconvenience, but better than nothing.