The spider, after spinning its web, will then wait on, or near, the web for a prey animal to become trapped. The spider can sense the impact and struggle of a prey animal by vibrations transmitted along the web lines.
Spiders do not usually adhere to their own webs. However, they are not immune to their own glue. Some of the strands of the web are sticky, and others are not. For example, if a spider has chosen to wait along the outer edges of its web, it may spin a non-sticky prey or signal line to the web hub to monitor web movement. Spiders have to be careful to only climb on the non-sticky strands of their webs.
(courtesy of wikipedia.com)
A pest is an organism which has characteristics that are regarded as injurious or unwanted. This is most often because it causes damage to agriculture through feeding on crops or parasitising livestock, such as codling moth on apples, or boll weevil on cotton.
The term pest may be used to refer specifically to harmful animals but is also often taken to mean all harmful organisms including insects, weeds, mites, fungi and viruses. Pesticides are chemicals that are used to control or protect other organisms from pests.
It is possible for an animal to be a pest in one setting but beneficial or domesticated in another (for example, European rabbits introduced to Australia caused ecological damage beyond the scale they inflicted in their natural habitat). The Western honey bee, one of the most beneficial of all insects, is itself a pest when it escapes into the wild in the Western Hemisphere, where it is not native (e.g., "killer bees"). Many weeds are also seen as useful under certain conditions, for instance Patterson's curse is often valued as food for bees and as a wildflower, even though it can poison livestock.
