Aphids

While we were raking leaves under our paper birch tree, we saw that we had little bugs on us.  We looked up at the leaves on the tree, and we saw these aphids all over the leaves.  I think there were thousands of them in our tree.  We looked them up in our bug book, and we are guessing that they are cotton aphids, but we are not sure.  Cotton aphids change color depending on the season: in spring they are light yellow, dark green in the summer, and dark brown or black in the fall.  We caught a bunch of them and put them in the bug playground with our ladybug for food.  Ladybugs eat aphids and black flies.