I found this large bag of flies at one of those stores where all items cost $1. When telling the story of the Ten Plagues, I put the plastic flies on the plate of snacks. When it became snack time, I went to get the snacks and was dramatically grossed out and showed the children what happened! They were horrified at the sight. We discussed how the Egyptians felt about the flies everywhere. Then we pulled out another plate of snacks to eat without the flies all over it. The first thing they told their parents when the parents picked them up was about the flies all over their food! Made an impression on them.