It made me mad and I sneaked up to the pigeon loft and put a tiny pin prick in all the eggs in the nests.

This was invisible but it caused the eggs to rot as he said mine had, and I felt that this was only justice.

Turn about is fair play.
When Jack's eggs didn't hatch he suspected me, for I had been so foolish as to predict that his eggs wouldn't hatch.

And so he was sure I was responsible, although he didn't know how.

In fact his mother had seen me enter the barn and had told Jack about it.