Insects have fascinating bodies, and one of the goals of close-up nature photography is to bring out all the colour and detail of insect life. Good macro photography puts the camera's focus on the eyes, legs, and bodies of these bugs, and their tiny world. For example, taking a photograph of a spider in its web tells a more interesting story.
Background colour plays an important role in composition. If the subject is dark coloured, as many insects are, a lighter, out-of-focus background will make the creature stand out from its surroundings and focus the viewers' attention on it.
The technique for getting an insect to stand out from the background is to use a shallow depth of field. Depth of field is defined as the area in front of and behind the subject that is in focus. Depth of field is determined by the aperture setting. Low f stops like f/2.8 will give you a shallow depth of field, which pinpoints the focus on your subject while the background goes out of focus.
Another technique that nature photographers use is to position their camera so that a brightly lit subject is photographed against a dark background. Exposing for a well-lit subject, under full daylight for example, or with a fill flash, will cause a dark background to underexpose and appear almost black. This effect creates a dark, even background, making the subject stand out.
But if the subject and background are both brightly lit, the insect may be difficult to separate from its surroundings. Placing a household item like a piece of cloth or paper behind the subject can work as a portable studio backdrop, isolating the bug against a plain background and setting it apart from its surroundings.
Insects are more mobile in warm weather: photograph them in the early morning or evening when it is cooler, and they will be moving slower. The available light at these times of day will be more flattering too.