Not invited visitors

Last year I experienced just focal damage on my box parterre due to the new introduced pest in middle Europe, the box tree pyralid (Glyphodes perspectalis). This small moth from Asia may cause relevant damages, with the caterpillars that can complete defoliate a parterre. This year the problem is more relevant with hundreds of caterpillars feeding on my plants. Well yesterday evening I treated the plants bit spores of Bacillus thuringiensis. I hope I can keep the problem under control without chemicals.