Daylilies are not deer resistant. According to Rutgers New Jersey Agricultural Experiment Station, daylilies are categorized as "Occasionally Severely Damaged" by deer. The Rutgers scientists recommend plants in this category should be protected by fencing or repellents to minimize damage in areas populated by deer.
Very few plants are fully deer resistant. If desperate, deer eat just about anything. What they eat may vary depending on what is available during each season in a given area.
Deer dislike poisonous plants, such as daffodils and poppies. They also avoid especially fragrant plants, such as herbs and lavenders. Deer rarely bother with prickly plants unless there are no other options.