Jigger (j&ibreve_;gg&etilde_;r), n. [A corrupt. of chigre.] 1. (Zoöl.) A species of flea (Tunga penetrans, or Sarcopsylla penetrans, or Pulex penetrans), which burrows beneath the skin; called also jigger flea. See Chigoe.
[1913 Webster]

2. (Zoöl.) Any one of several species of small red mites (esp. Tetranychus irritans and Tetranychus Americanus) of the family Trombiculidae, which, in the larval or leptus stage, burrow beneath the skin of man and various animals, causing great annoyance. Also called chigger. [Southern U. S.]
[Webster 1913 Suppl. +PJC]

Jigger (?), v. t. [Cf. Jiggle.] To move, send, or drive with a jerk; to jerk; also, to drive or send over with a jerk, as a golf ball.

He could jigger the ball o'er a steeple tall as most men would jigger a cop. Harper's Mag.
[Webster 1913 Suppl.]