I planted some boxwoods this year and I've been amazed at how they are attracting wasps. What is the draw? Are the wasps looking for insects?
Usually that is what one or a few wasps are doing in summer around plants. They can smell larva-chewed leaves from a distance, or may just be hoping for the best on your plant. Are there aphids on the newest growth?
Certain odors may entice them; every summer a few nose around my plastic rain gutters for weeks with no apparent benefit.