The world is populated by an abundance of flies and insects and identifying them may be quite a challenge. As a general rule, all insects are equipped with six legs and have three body parts: the head, thorax and abdomen. Because there are thousands of species of flies and insects, careful evaluation of the insect is important. Arm yourself with a good magnifying glass to see the smallest details of your insects. With a great book, you'll also have lots of images that provide a basis for comparison.
Place the insect or fly in the jar. Placing the bug in the jar will make it easier to identify since it cannot escape and its movements will be limited. Once safely in the jar, you can also look at it carefully without risking a sting, in case the insect is capable of doing so.
Observe the wings using your magnifying glass. Most insects have two pairs of wings composed by two forewings and two hind wings attached to the thorax. On the other hand, flies only have one pair of wings, the forewings. The lacking hind wings are replaced by tiny knobs known as halters, which allow them to do somersaults in the air.
Assess if the specimen belongs to a specific group. This will help you narrow down your search. For instance, beetles belong to the Coleoptera group; ants, bees and wasps belong to the Hymenoptera group; moths and butterflies belong to the Lepidoptera group; and mosquitoes and flies belong to the Diptera group.
Look for similarities between your specimen and the specimens listed within the group. At this point, you must look well with the magnifying glass to recognise minute details that differentiate one species from another. To ensure you have made the right match, read all the information pertaining to the insect's or fly's habits. That can include where the insect typically lives, time of the day it's more likely to be seen and other details that will help make identification easy.
Consider that if the specimen does not have three body and six legs, it is not an insect. If the specimen has eight legs, you likely are dealing with an arachnid. Unless you are dealing with a pest, release your insect from the jar after successful identification. Taking pictures of the insect is helpful for future reference.
Use caution when handling the insect for inspection; some may sting and may cause allergic reactions. Ensure your insect cannot escape from the jar during inspection.