The form and function of the mouthparts in adult Lepidoptera and their feeding behavior are reviewed from evolutionary and ecological points of view. The formation of the suctorial proboscis encompasses a fluid-tight food tube, special linking structures, modified sensory equipment, and novel intrinsic musculature. The evolution of these functionally important traits can be reconstructed within the Lepidoptera. The proboscis movements are explained by a hydraulic mechanism for uncoiling, whereas recoiling is governed by the intrinsic proboscis musculature and the cuticular elasticity. Fluid uptake is accomplished by the action of the cranial sucking pump, which enables uptake of a wide range of fluid quantities from different food sources. Nectar-feeding species exhibit stereotypical proboscis movements during flower handling. Behavioral modifications and derived proboscis morphology are often associated with specialized feeding preferences or an obligatory switch to alternative food sources.

Urbanization is a global phenomenon that is encroaching on natural habitats and decreasing biodiversity, although it is creating new habitats for some species. The Eurasian kestrel (Falco tinnunculus) is frequently associated with urbanized landscapes but it is unclear what lies behind the high densities of kestrels in the urban environment.

Many species of nymphalid butterflies only exceptionally visit flowers and feed instead on tree sap, juice of rotting fruits and other decaying substances. To investigate whether the proboscis morphology of these non‐flower‐visiting Nymphalidae differs from that of nectarivorous butterflies, representatives from 64 nymphalid species with known feeding preferences were examined. Morphometric comparison of the proboscis revealed characteristic differences in proboscis length, tip‐region length, wall composition, and number and shape of proboscis sensilla between these two feeding guilds. The investigated non‐flower‐visiting species belonging to Apaturinae, Limenitidinae, Morphinae, Brassolinae, Nymphalinae and Satyrinae, possess a relatively short and light‐coloured proboscis which has a long tip‐region with a great number of club‐shaped sensilla styloconica. Densely arranged, these sensilla form a flat brush located laterally from the openings into the food canal on the dorsal side of the tip‐region. Among the non‐flower‐visiting species, a second type of proboscis was found in fruit‐feeding Charaxinae the stout tip‐region of which is equipped with more widely spaced sensilla styloconica. The investigated flower‐visiting Heliconiinae, Nymphalinae, Satyrinae, Danainae and Ithomiinae are characterized by a slender, darker‐coloured proboscis with a rather short tip‐region bearing fewer sensilla styloconica in a loose arrangement. Discriminant analysis revealed that the tip‐region length, the number of sensilla styloconica and the relative proboscis length are the most important discriminating variables between the flower‐visiting and the non‐flower‐visiting species. The proboscis morphology of nymphalid butterflies corresponds with certain feeding habits and allow us to make predictions on their food preferences. The ‘brush‐tipped’ proboscis seems to have a functional role in the accumulation of fluid and the uptake of liquid from wet surfaces such as rotting fruits or tree sap. We conclude from the phylogeny of the examined taxa that this derived proboscis tip morphology evolved several times independently as an adaptation to the exploitation of new food resources.

Female Pangoniinae in the tabanid fly genus Philoliche can display remarkably elongated proboscis lengths, which are adapted for both blood- and nectar-feeding. Apart from their role as blood-sucking pests, they represent important pollinators of the South African flora. This study examines the morphology of the feeding apparatus of two species of long-proboscid Tabanidae: Philoliche rostrata and Philoliche gulosa - both species display adaptations for feeding from a diverse guild of long-tubed flowers, and on vertebrate blood. The heavily sclerotised proboscis can be divided into two functional units. The short, proximal piercing part is composed of the labrum-epipharynx unit, the hypopharynx and paired mandible and maxilla. The foldable distal part is composed of the prementum of the labium which solely forms the food canal and is responsible for nectar uptake via the apical labella. The proboscis works as a drinking straw, relying on a pressure gradient provided by a two-part suction pump in the head. Both proboscis and body lengths and suction pump dimensions show a significantly correlated allometric relationship with each other. This study provides detailed insights into the adaptations for a dual diet using an elongated sucking proboscis, and considers these adaptations in the context of the evolution of nectar feeding in Brachycera.