Q.Spanish Broom Plants
I planted four Spanish brooms in March and they are just now starting to do well. However, I noticed a bunch of new sprouts looking dead and upon a closer look saw numerous very small little yellow/black caterpillars that had invaded. I have been unable to find out what these are, but I was told that an insecticidal soap would take care of the problem. Would you agree with this advice. Thank you.
Yes, insecticidal soap should work fine. You may also want to consider using neem oil or Bt (Bacillus thuringiensis). Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm