Redbacks are the ones worth taking seriously: roller-door tracks, under outdoor furniture, inside stacked pots, the corner of the letterbox. Dry, sheltered, undisturbed. Black house spiders build the messy funnels in window frames and under eaves. White-tails come inside hunting them, so cutting white-tail numbers starts with cutting the black house spider population.
The visit opens with a de-web, because a residual sprayed over an existing web never reaches the spider beneath it. Then eaves, architraves, sills, door frames, subfloor, shed and garage tracks. Activity climbs from October and peaks with the males wandering in late summer, so a spring treatment is the one that counts. Odd dead ones for a fortnight afterwards is the residual working.