Next you sit back and wait about 10 days for the webs to re-establish signaling where the active spiders are. This is where the spider control experts come in. Depending on the what they find, they are likely to start by administering an external surface treatment which is applied in areas where spiders typically crawl.
Most professional treatments work on residual contact meaning the insect will absorb the product after crawling over it, effectively exterminating it. On the internal surfaces, residual product is usually only applied as required.
Now you leave remaining cobwebs for at least 6 weeks after treatment so that visiting spiders (like our white tailed friends) will come in contact with the product. Webs can then be brushed away with a broom or duster. Don’t use water to clean these surfaces as it will wash the product away.