From around 1814 Wiedemann devoted much of his time to taxonomic entomology and in 1815, on a visit to Bonn to stay with his daughter Emma who had married Carl Theodor Welcker later a radical embroiled in the turbulent politics of the 1840s he travelled to Stolberg to meet Johann Wilhelm Meigen a, by then, well known entomologist through his important work on Diptera. Perhaps, not able to attend properly to his medical duties through ill health- he visited the spa town of Bad Aachen in 1817- Wiedemann changed employment (to Pharmacology) and had several semi-honorary positions. With more time and sedentary, he prepared and studied insects and went on collecting trips for his health. He also gaves lectures on entomology and natural history.