as you might guess from the name, Milesia crabroniformis is a mimic of european hornets (Vespa crabro) and does a surprisingly good job of it, from the size to the buzzing, often giving me false hopes that i've found an actual hornet since they're not common here. ironically, what tends to give them away is their overly aggressive behavior - only a hoverfly would divebomb your face repeatedly the way they do