You could, if you're really smart, you could shine a nonlethal laser on the bug before you zap it, and you could listen to the wing beat frequency and you could measure the size.
如果你真的很聪明，你可以 在你杀死这些虫子之前 向它射出一束不具杀伤力的激光， 你可以仔细听它扇动翅膀的频率， 可以估计它的大小。