For insect shots, having a smaller Aperture value (e.g., F8) will gives you a higher Depth of Field (DOF), hence resulting in most or all parts of the insect to be clear. Using a bigger Aperture (e.g., F2.8) will have a shallow DOF.
there's a compromise though. a smaller aperture (large number) will mean that the shutter need to open longer. if the lighting is not bright enough, movement of the insects might cause blurrness.
Originally posted by mpenza there's a compromise though. a smaller aperture (large number) will mean that the shutter need to open longer. if the lighting is not bright enough, movement of the insects might cause blurrness.