Think about it: webs catch insects that intrude in your home through air holes. So if a spider is smart, where does he put his web?
You guessed it: by the air leaks. If you find spiderwebs in your house, theres a good chance there's an oppertunity for air sealing.
Testimonials
I realized the first winter that I spent in my new home in Vestal New York that the insulation was insufficient. The house never had a warm comfortable feeling. The bedrooms above the garage were especially cold and the floors freezing to bare feet.
Richard F., Vestal, NY