If you are writing about Astilbe, these are shade loving perennials that come back each spring. They like moist soil so water them often. The tiny pin holes could be from weevils that lay eggs  in the soil then hatch and climb up the plant to feed on the leaves at night. They do their damage in June then mature and leave the plant. They are very hard to see when young and of course at night. I would wait to see if the problem goes away in July as the weevils mature. You can also try a insecticidal spray that has weevils listed as one of the pests that it kills but I would spray as a last resort. Keeping the soil moist and growing the astilbe  in the shade is your best defence as strong plants are more weevil resistant. Keep growing, Marianne Binetti  P.S. Welcome to gardening and don't let this little problem get you down - next year the plants will be even larger.