Semicolons and Colons
Use a semicolon to join two closely related independent clauses.
Leopards usually hunt at night; the dark helps them to ambush their prey.
Note that both sides of the semicolon must be complete thoughts. The following is incorrect.
Leopards usually hunt at night; ambushing their prey in the dark.
If the second clause is not closely related, use a period rather than a semicolon.
Leopards usually hunt at night. Their prey includes antelope.
Also use a semicolon if a series of items has internal commas.
The lake contained many fish including minnows, sunfish, and bass; a few mammals including otters, muskrats, and beavers; but no amphibians.
Use a colon to join two equivalent elements.
Lions hunt many prey species: impala, zebra, wildebeest, gazelle, etc.