"Insects evolved an astonishing diversity of different mouthpart and head capsule types optimally adapted to ingest their particular food recourses. Among early winged insects, mayflies (Ephemeroptera), dragonflies (Odonata), and Polyneoptera (including grasshoppers, cockroaches and allies) show biting-chewing mouthparts, while bark and true lice (Psocodea) possess ""intermediate"" mouthparts commonly known as a 'mortar-pestle type'. Thrips (Thysanoptera) and true bugs (Hemiptera) show piercing-sucking mouthparts, together they are known as Condylognatha, the most speciose insect group after Holometabola. How the transition from one mouthpart type to the other could have happened is unclear. The ultimate goal of this project is to explain and quantify to mechanical transition from chewing-biting to piercing-sucking mouthparts in ""basal"" winged insects taking into account recent as well as fossil species. Subsequently, the results will be used to model the head evolution of insects under a range of other factors such as ecology, phylogeny and development in order to better understand the influence of these factors on insect head evolution. A mechanical state-of-the-art characterisation of biting-chewing and piercing sucking insect mouthparts in the context of insect head evolution has not been done so far on a larger scale. Therefore this project will characterize the mechanics in recent biting-chewing insects (Work package, WP1), in recent piercing-sucking insects (WP2), and in selected fossil biting-chewing and piercing-sucking insects (WP3; see Figure 4). In parallel, the PI project (WP4) will deal with the development of algorithms to model evolutionary processes of mouthpart and head capsule change in relation to other factors besides the mechanical ones."