The southern green stink bug, Nezara viridula (Hemiptera: Pentatomidae), is perhaps the most serious pest of macadamia nut because it is unpredictable. In bad years, N. viridula can cause serious economic losses and threaten the economic viability of macadamia nut production for some farmers. Monitoring stink bugs in tree crops is notoriously difficult as there are no traps or lures. We used ruthenium red dye to stain stink bug probes and monitor feeding activity throughout the year in mature and immature nuts. The inside of the husk was the best location to detect the red stain. Stains to the inside husk were highly correlated (0.68-0.80) with kernel damage, suggesting this technique can be useful for growers to forecast stink bug injury during nut development and before first harvest. This will give growers time to consider and evaluate stink bug pest management options (e.g. insecticides, mowing, weed control).