Arnold, C., & Sengonca, C. 2000 Die Wollige Napfschildlaus Pulvinaria regalis Canard - ein Problem fur Strassen- und Alleebaume unserer Stadte? [Is the horse chestnut scale Pulvinaria regalis Canard (Homoptera, Coccidae) a problem for ornamental tress in urban areas or not?].. Mitteilungen der Deutschen Gesellschaft für Allgemeine und Angewandte Entomologie. Bremen 12(1-6): 93-96.

Notes: A study was conducted in Germany during 1998 to determine the intensity of horse chestnut scale (Pulvinaria regalis) infestation on ornamental trees (chestnut, lime and maple) in Bonn, Duisburg, Karlsruhe and Zurich. In related experiments, the population dynamics of P. regalis and their natural enemies were monitored in Bonn and Zurich during 1997-98. The highest infestation level was observed in Duisburg on chestnut trees with 57400 larvae/m2 leaf area. The number of larvae decreased to nearly 30000 individuals on maple and lime trees. In Karlsruhe and Zurich, lime trees were the most infested followed by maple and chestnut. The population dynamics of P. regalis in Bonn steadily increased on all 3 host species. In Zurich, the infestation level of P. regalis on chestnut trees stagnated, whereas a slight increase on maple and an outbreak on lime trees occurred. Four species, namely Exochomus quadripustulatus, Leucopis sp., Coccophagus scutellaris and C. lycimnia were identified as natural enemies of P. regalis.