What do we spray to prevent the bugs

Question

Every year our Laburnum tree gets tiny worms after it blooms. They eat the leaves and leave the tree looking awful

Answer 1

Here is an extension publication that discusses caterpillars eating the leaves. It advises using applications of Bacillus thuringiensis (Bt) as soon as the larvae hatch.

http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/folfeedcater.html