Philaenus spumarius is the primary insect vector of Xylella fastidiosa, a pathogen responsible for infecting more than 700 plant species worldwide. Determining this vector’s host preferences is crucial for understanding vector-plant-pathogen dynamics and, consequently, for developing effective control strategies. In this study, the preference of P. spumarius was evaluated through multiple-choice tests using ten plant species representative of a cork oak forest in northeastern Portugal. The tests were conducted in a greenhouse under controlled temperature and natural photoperiod. For each replicate, five specimens of each plant species were arranged radially and equidistantly from a central release point, where 30 fasting (4 h) adult P. spumarius were released simultaneously. Insect choice was recorded 2, 4, 6, 8, 12, and 24 hours after release. Ruscus aculeatus showed the highest preference, attracting a total of 169 insects (mean of 1.78 ± 0.59 per count), followed by Quercus pyrenaica with a total of 131 insects (mean of 1.93 ± 0.41). In contrast, Quercus suber and Quercus ilex were the least preferred species, while Thymus mastichina, Calluna vulgaris, and Arbutus unedo showed intermediate attractiveness. These results allow for the identification of the vector’s preferred hosts in forest ecosystems, providing fundamental data for modeling and managing the epidemiological risk of X. fastidiosa in Mediterranean forests.