The presence of cockroaches in urban environments is more and more frequent whatever the type of building. Pest control programmes generally consist of insecticide applications. Several reasons, like their expense or incorrect application, can explain why results are not satisfactory, not to mention the development of insecticide resistance. It must be stressed that the aim of pesticide control in urban areas is not only to reduce the pest population to an acceptable level, but to eliminate it completely. The aim of this investigation was to analyse the results of an insecticide treatment campaign in cockroach (Blattella germanica (L.))-infested council flats in order to understand why these treatments failed. A multivariate analysis revealed that several environmental factors like the number of residents/m2 or the degree of cleanliness could explain, at least in part, the presence Of cockroaches in flats.
