Can you tell me what to use to "seal" the weep holes on my house?

This is the first time I have lived in a house that has weep holes. I have to say it is shocking to me that large holes are around my house for mice, snakes, and insects to crawl into. From what I understand there is a building code that the houose must have weep holes, but no code that they have to be sealed in a way that will let the moisture out, but not let everything else in. I bought some screening material made from aluminum, but in the larger weep holes it just falls through into the wall. What can I use to hold the screening in place? I am open to any ideas you might have to help the situation.

Also, on one side of my house the holes are at ground level. We had a crazy storm several months ago and water cames into the rooms. I think since the land there was not graded well and it was basically a flash flood type situation, water poured into the weep holes. I want to put some sort of waterproof seal at the bottom of the weep hole, close it up at least an inch in that one area. What should I use? I already regraded and laid down pebbles to help drainage.