If it's a butterfly, or more likely a moth, the adults won't eat your plant.
Surface poisons are ineffective.
They fly in, lay eggs, and fly off.

Systemic poisons don't kill caterpillars until they start munching.
So, it prevents maturing and laying more eggs, but does not help the plant that is now somewhat toxic to us.

At this late stage, hand removal before they hatch is the best action.
These eggs are quite large and white.
The new hatch will color match their food and will be very hard to see.
So, squish early, and often.

The bud-worms that start bud mold have much smaller eggs, and they get laid one or two at a time inside the buds.
For them, I use dryer sheets to repel the moths before they can lay eggs.
Works a treat.

Aloha,
Weezard