The imagines were found during the period between June 26 and August 3, 1995. The first specimens flew in the southern area near the forest edges on the last days in June, when the climate was most favourable in this area. Their abundance afterwards increased to a maximum during the period between June 30 and July 20. At this time, D. diadema could be found in all open areas; usually at a density of about 1 specimen per 10 square metres.