As babies, Maneaters are considered items and have similar properties as other items; they are programmed to be conductive, but will realistically not be stricken by lightning.
This is because at the start of a day, a timer waits 15 seconds to create a list of all spawned conductive items, and this list is never updated throughout the day. Maneaters, as indoor enemies, usually do not spawn at the start of the day, and will then not fit within that 15 seconds to be added.*
(This also means that any equipment delivered that day will not be struck by lightning.)
If a Maneater does spawn in the first 15 seconds, either naturally or artificially, it will be added to the list and struck by lightning when outside. This causes an explosion to "damage" the Maneater, decreasing its transform timer (which is also decreased by being outside).
Once the Maneater transforms, it will not stop being struck by lightning -- this is because the baby "item", while disabled, can still be struck by lightning, and moves with the adult Maneater. After 6 strikes, it will die.
*Occasionally, on the final day of a quota (0 days left), the spawn curve can be altered enough so that indoor enemies can spawn at the beginning of a day. This is still incredibly rare and difficult to replicate.
(Information provided by butterystancakes on Discord and ILSpy decompiling. Using Imperium for spawning, BringBackTheBaby for keeping the baby from constantly crying outside, and a Unity build of the current version. Otherwise completely vanilla.)
