Magalhães Silva, G., & Carmona, M.M. 1988 Nota sobre a existência actual em Portugal continental de Kermes vermilio Planchon (Homoptera: Coccoidea) a grã-dos-tintureiros ou grã-de-carrasco. [Note on the actual existence of Kermes vermilio (Homoptera: Cocoidea) in continental Portugal.]. Agronomia Lusitana 43(1-4): 5-19.
Notes: This species has been proven to be the only one responsible for the dye used in ancient times and collected from Quercus coccifera. The possible causes (biotic and abiotic) for its current extreme scarcity are discussed. A second species of the same genus, K. ilicis, has also been found in Portugal, both on Q. coccifera and Q. suber. Two species of encyrtid parasitoids were also found: Aenasioidea hispanica and Blastothrix erythrostethus.