A Midget

1. (originally) A little sandfly.
2. (loosely) Any small swarming insect similar to the mosquito; a midge.
3. (sometimes offensive) A normally proportioned person with small stature, usually defined as reaching an adult height less than 4'10". [from later 19th c.]
4. (sometimes offensive) Any short person.
5. (attributively) A small version of something; miniature.

Used for an insect, this is a variation on midge that is incorrect but commonly used.

(person below 4'10"): dwarf (loosely), little person

(derogatory: any small person): dwarf, short-arse, shortie/shorty, tich/titch, vertically challenged person (humorous)

(swarming insect): midge

(miniature): dwarf

(derogatory: any small person): giant

(miniature): giant