Geranium, penstemons and petunias sometimes become infested by budworms.  Foliage may be chewed, flowers may open tattered and full of holes or appear dried up and not open at all.   Tiny black droppings on the foliage are left behind. The striped caterpillar larval form of a native moth is a close relative of the corn ear worm, the tobacco or geranium budworm.  Moths lay eggs singly on host plants.  After hatching, the caterpillars chew fully opened flowers and occasionally dine on the leaves.  Spraying early on with organic BT is effective if done before the worms burrow inside the flower buds.  Remove dried up buds and flowers that may harbor the caterpillars and pull up and destroy ragged, end-of-season petunias that my have eggs sticking to the plant remains.  There may be two generations per year so preventative spraying with BT may protect established plants of geraniums or penstemon.