High-flying vestals?

I seem to remember Matthew wondering why he didn’t get too many vestals, considering his coastal situation compared with traps run inland. I’m 10 miles from the coast, and get a diluted selection of migrants. This year I’ve caught 4 vestals (two in Aug, 1 in Sept and 1in Oct), but not many other migrants. I wonder if, as has been proved recently for the painted lady, vestals migrate at a greater altitude and don’t descend to garden/field height until they are inland. It would be interesting to compare and contrast.