If you must do something now, spray in a strong permethrin via a tube.
Bengal Roach Spray is excellent (albeit pricey), uses a dry refrigerant
carrier that evaps immediately, leaving surface residue as well as a
penetrating dry fog. Cheap sprays are water based and very weakly
concentrated by comparison.
Put some no-pest type strip in the hole. This lets them out in
desperation (so they don't bore through into the interior of your house
elsewhere--watch out for this in any case!), but repels and/or slow-
poisons the returning workers.
Poor man's repellant: rope or felt saturated with kerosene.
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