I didn’t know what a spider hole is. Now I do. William Safire explains in the NYT:
Another useful bit of information is the origin of “spider hole,” a phrase used by Lt. Gen. Ricardo Sanchez to describe the dugout hiding place in which the fugitive Saddam was cowering.
This is Army lingo from the Vietnam era. The Vietcong guerrillas dug “Cu Chi tunnels” often connected to what the G.I.’s called “spider holes” — space dug deep enough for the placement of a clay pot large enough to hold a crouching man, covered by a wooden plank and concealed with leaves. When an American patrol passed, the Vietcong would spring out, shooting. But the hole had its dangers; if the pot broke or cracked, the guerrilla could be attacked by poisonous spiders or snakes. Hence, “spider hole.”
(via The Belgravia Dispatch)