How many times have you cleaned the corners and after a day the spider webs are again there? Every housewife knows how annoying they are and how tough it is to get rid of them. Unfortunately, very often I see a lot of old spider webs filled with dead flies, dust and other rubbish. That is because home keepers are too tired of the war with spiders.
Spider are environmentally friendly, (example) when you want to control flies. When they have to do a new web, they eat the old one. If you are spider-friendly you have to leave the spider live. Sometimes you might clean the dust and other inedible bits, because spiders won't eat them.
