Helsen, H.H.M., Blommers, L.H.M., & Trapman, M.C. 1996 Timing observation and control of mussel scale Lepidosaphes ulmi.. IOBC/WPRS Bulletin 19: 145-149.

Notes: [This paper was presented at the International Conference on Integrated Fruit Production (Polesny, Muller & Olszak, Eds.) held at Cedzyna, Poland, 28 August - 2 September 1995.] Lepidosaphes ulmi is a locally important pest in apple and pear orchards in the Netherlands. Even light infestations can cause severe economic loss due to a zero tolerance on fruits for export. The optimal time for chemical control is when all crawlers have emerged from under the scales. A temperature sum model was developed to indicate the best moment for observation and subsequent control.