Ir is the prefix of irresponsible. Ir means 'to not'
<em>Hope it helps</em>
To give a picture of the behavior of the grasshoppers would be my first choice but it could also be to show the violence of nature
When they spot the huge terrifying dinosaur, though, Eckels panics, inadvertently stepping off the path and crushing a single butterfly. That tiny difference is enough to unloose a chain of events so that by the time they get back to the future, it is irreparably changed.