Isotopic fractionation in a large herbivorous insect, the Auckland tree weta

▶ Tissue fractionation for C and N differs between tissues. ▶ Similarity in isotope values for captive leaf-fed and wild individuals supports herbivory. ▶ Whole-body isotope values in captive tree weta demonstrate trophic depletion (Δδ) for δ15N of about −0.77‰ and trophic enrichment of 4.28‰ for δ13C. ▶ Food availability and foraging traits may contribute to wide isotopic variation among wild individuals.