Green’s Dictionary of Slang

tarantula-juice n.

inferior whisky.

1861		R.F. Burton City of the Saints 30: He can do nothing without whisky, which he loves to call tarantula-juice [...] and many other hard and grotesque names.
1876		‘Dan de Quille’ Big Bonanza (1947) 285: But let me come home full of tangle-leg, sheep-herder’s delight, and tarant’ler juice, and that is the durndest shamedest dog above ground.
1889		H. O’Reilly Fifty Years on the Trail 126: The quantity of ‘Tarantula juice’ we had to drink to keep our circulation going was surprising. ‘Tarantula juice’ is two quarts alcohol, a few burnt peaches, a plug of black tobacco, put in a keg and filled up to five gallons of water.
1931		J.F. Dobie Coronado’s Children 28: The Comanches brought in a jug of fire water — regular old tarantula juice — from somewhere and they all got as drunk as a covey of biled owls [DA].
1936		R.F. Adams Cowboy Lingo 228: The Westerner’s names for whiskey were legion [...] ‘tarantula juice.’.