When Don went to visit goldenrod plants, he found a gall on a stem.
The gall was a part of the stem that had grown large and round. It was the home of a little insect.
The insect that lived in this gall was a baby fly. It was white. It had no wings or legs. A baby fly is called a maggot.
When the maggot was hungry it ate some of the inside part of the gall. The gall was its home and its food, too.
The maggot ate gall food and grew fat. Then it rested without food.
The young gall insect was quiet all winter. In the spring its six legs and two wings grew.
Then it was not a maggot any more. It was a grown fly with dark wings.
The grown fly could not eat the same kind of food the maggot did.
The gall was not a good home for a grown fly. So the fly came out and flew away.
There was a little round hole in the gall where the fly came out.
When the fly with the pretty dark wings was ready to lay her eggs, she went to some goldenrod stems. She put each egg in a good place on a green growing stem.
Then the goldenrod stem began to grow in a queer way. It grew like a big round ball around the egg.
There was a baby maggot in the egg. When the maggot hatched it was in a round gall. The gall was its good home and its food, too.