From Nookipedia, the Animal Crossing wiki
The following is a list of bugs in Animal Crossing: New Leaf that are available during May. Note that this applies only to bugs that are part of the mainland, and not on Tortimer Island.
May bugs in New Leaf
New in May
Leaving after May
Bugs leaving after May in Animal Crossing: New Leaf
|| 280 Bells
||Very uncommon (D)