I don't know any caterpillar that eats orchids or plumeria. Maybe some of the moths that are generalists like Armyworms. They eat everything. Keeping squirrels from eating orchid blooms has always been my problem! Butterfly caterpillars, and to a certain extent, moth caterpillars, are pretty specific and will not deviate from their host plants. And even in certain regions they'll prefer one host plant to another.
