Why Aren't Spiders Trapped In Their Own Webs?

When a fly or mosquito or any other tiny creatures comes in the web of a spider, it gets caught by the web because of its stickiness. Those tiny creatures are then trapped by the sticky materials within the fine webs and the spider eats them as a nice meal.

So the question is, if there is a sticky material within the web, how is it possible that the spiders do not get caught by it? But very surprisingly, the spider may also get caught by it, but usually it doesn't 'at home'. Because the spider forms their webs using two types of materials, one is sticky type forming the sticky part of the web, the other one is non-sticky material, forming the structure of the web. The spiders are excellent is their touch sensation. Using this quality, they are able to distinguish the pathway of non-sticky web and move through it only. And naturally they themselves don't get trapped.