First find the common denominator. In this case, you would want to use 32. So, 1/4 = 8/32. So, an ant is 8/32 of an inch and an aphid is 3/32 of an inch. Now to find the difference, you subract. 8/32 - 3/32 = 5/32. So the answer is, the ant is 5/32 of an inch longer.