Answer: Sounds like they really liked that particular bush! Adult moths or butterflies lay eggs on the plants they determine will support the larvae when they hatch. That particular shrub must have been perfect for the offspring. Without knowing the name of the shrub I can't tell you whether the larvae will turn into moths or butterflies. It may be an isolated incident and you may not need to control them next year. But if it is a reoccuring problem, you can use Bt (sold as Dipel or Thuricide) to control the caterpillars. I tend to just leave them alone - just in case they turn into beautiful butterflies!
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