Now, what would you do if you saw this Insect crawling along the lawn or on the trunk of a tree? Please note that this insect's body is about 3 inches and the ovipositor, the long thing at the back is sometimes up to 5 inches long! We probably all would have the same reaction...squish it! Spray it with a nasty chemical! Get it out of here!
But that is the wrong reaction... this is an ichneumon wasp, and the ovipositor, or egg-laying structure - is long so the wasp can get deep into lawns or tree trunks where this parasitic wasp lays eggs on nasty larvae or insects. It is one of the 'good' bugs.
So, remember, do some research before squishing or spraying. You might be doing great harm to lots of beneficial insects in your garden if you consider everything to be a bad bug...