Some flies, including houseflies and blowflies, have specialised hindwings to help them take-off faster, making them trickier to catch
Source:
https://www.newscientist.com/article/2264602-houseflies-have-specialised-wings-that-make-them-harder-to-swat/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home