Dvar Torah for Sunday
By hail, locust, and darkness, HaShem told Moshe to stretch forth his hand. If so, why by hail and locust did Moshe stretch forth his staff, and by darkness he did not? (Look it up!)
The servants were able to do so by locust because it was then within the letter of the law to do so, because the plague of hail on the fearing servants as well (on their field produce) and the warning for locust already showed the need to do more. But hail came upon them without indication or further warning. And after the warning for locust, Pharaoh and the servants did what they needed to do, but the plague still came on them without indication or further warning. The plague showed that one is held responsible for not doing more. This message was for the yidden.
Darkness was not a sign because locust already showed them that they have to do more, and they did not.)