Studies on the biology of Prostepbunus truncatus (Horn) (Col., Bostricbidue) on woodThe adult survival period and the lifetime progeny of Proste banus truncutus were investigated on the wood of Manzbot esculenta and Poincinza regia. O n M . escuinta there was a slight mortality from the beginning of the trial which caused a slow decrease of the population. The maximum survival period lasted between 40 and 44 weeks. O n P. regia the population of P. truncatus decreased faster than on M . esculenta. The maximum survival period was between 24 and 30 weeks. The survival curves of male and female adults had a similar shape on both media. The number of eggs laid in average per female during lifetime was 186 on M . esculenta and 52 on P. regia. The determination of the larval instars by measuring the width of the frontoclypeus was practicable on M . esculenta. The measures were separated into 3 distinguishable classes which could be expected as the 3 larval instars. O n P. regia and 3. trugucuntba there were no distinguishable classes of measures, though a clear determination of the larval instars was not possible.