During a recent dry spell in the Brisbane area the canal situated at Nundah, known as Schultz's, had become silted, and various aquatic and other weeds had taken possession of the bed. Owing to pollution from a sewer, produced higher up, Culex fatigans, as is usual on such occasions, was breeding amongst the aquatic vegetation consisting mainly of Eichhornia speciosa (Water Hyacinth), Hydrilla verticillata (Water Thyme) and Jussiaea repens (Yellow Primrose). The large quantities of Characeae, usually so abundant in this canal during wet tunes, had completely disappeared.