Soria, S., Del Estal Padillo, P., & Viñuela Sandoval, E. 1998 Physokermes hemicryphus (Dalman) y Xylococcus filiferus Low, dos coccidos forestales nuevos para la fauna espanola. [Physokermes hemicryphus (Dalman) and Xylococcus filiferus Low, two species of forest coccids new for the Spanish fauna].. Boletín de Sanidad Vegetal, Plagas 24: 2, 219-224.

Notes: Physokermes hemicryphus is a pest of Picea abies. The species is already known in Europe and North America, but has been found for the first time in Spain (Madrid, Segovia and Valencia). The European species Xylococcus filiferus develops on Tilia sp. It is well known in some countries of central Europe, but has been found for the first time in Spain (Segovia). Data on biological characteristics and host damage are provided for both species.