An assemblage of moth species at a suburb of Prague (50 degrees 5'11 '' N, 14 degrees 18'06 '' E) was monitored by a highly efficient mercury light trap for 23 years (1967-1976, 1980-1992). Species caught were divided into guilds according to habitat specialisation, and analysed using species richness S, Shannon's diversity H and evenness J as the response variables, and the individual years of monitoring and effects of mean annual temperature and precipitation as the explanatory variables.