Many plant species have evolved surfaces designed to reduce insect attachment. Among such plants are deceptive trap flowers of Ceropegia. Their gliding zones consist of epidermal cells each topped by a papilla secreting a single small liquid droplet on its tip. So far, the molecular and physical mechanisms controlling the function of these droplets are unknown. We analyzed the droplets of C. sandersonii flowers by microscopic approaches, studied how they behave when getting in contact with the feet of fly pollinators, and analyzed their chemical composition. The droplets contaminate the insect feet, on which they solidify. As its main component a negatively charged polysaccharide containing a β1,3-galactan backbone and Rhaa1,4GlcAβ1,6[Arafa1,3]Galβ1,6 side chains or truncated versions of it was identified by NMR spectroscopy. The chemical structure represents a rudiment version of an arabinogalactan, which is supported by its binding to β-D-glucosyl Yariv reagent. A proteomics approach revealed candidates of arabinogalactan proteins to which the polysaccharide is connected. The high amount of GlcA in the polysaccharide explains the unusual physical characteristics of the droplets like viscoelasticity and hygroscopy. We add a new function to arabinogalactan proteins, and discuss, why the identified polymer is well suited for catching and temporarily trapping of pollinators.