Here's how I would do it:
How far does he have to go to catch the bug ? 23.8 meters
How soon does he want to get there ? 1.8 seconds
What speed does he need ? (23.8 m) / (1.8 sec) = 13.222 m/sec
What speed is he flying now? 3.7m/s
How much does he need to increase it ? (13.222 - 3.7) = 9.5 m/s faster