Per the manufacturer, the holes on the Alpine Yellow Jacket Replacement Bait Stations are 5/8".
The Alpine Yellow Jacket Bait Stations would be a great option for yellow jackets. There are several species of yellow jackets that are not scavengers and would not be attracted to the stations. You use the stations by placing a mixture of tuna or other food attractant (see below for examples) with a small amount of onslaught insecticide in each Alpine bait station. The stations are then hung around the outside of the home, out of reach of children, but accessible to yellow jackets. We recommend trying out a few baits without the Onslaught before using the kit to ensure the species you are treating will take to a bait. A few recommended baits: raw chicken pieces, raw fish, canned tuna, cat food, or fruit.