Dependent on the species, time of day, behavior at the time you are shooting it. Handheld photo of insect grazing at flower at 1:2 - 1/250 is good, on burst mode, anticipating that minor shifts in your position (ie, breathing) or bug's position will get critical focus in some shots. Snoozing bug in early morning cool (hah! that means 80 degrees now) - you might manage 1/60 using the "Lord V" method of grabbing camera plus hiking pole (stick, whatever support) with non-shutter hand. Wind is also a problem.
Flash - eliminates all those pesky low shutter speed issues involving bug or leaf/stem movement. Figure out if you want a dark far background or a natural far background, adjust camera accordingly, and shoot. I am still learning the art of macro flash.