The fastest insect known to man is a species of Australian tiger beetle known as Cicindela hudsoni, which was recorded at 5.6 miles per hour. The next fastest is another Australian tiger beetle, Cicindela eburneola, which was observed in the same study to have a top speed of 4.2 miles per hour.
The common American cockroach is another fast moving species, having been clocked running on its two hind legs at 3.4 miles per hour. The cockroach has wings and is able to fly, but it moves much faster with its legs. The Australian tiger beetles also have wings, though they are vestigial and cannot be used.