Abstract: Two fields with corn (Zea mais) and giant reed (Arundo donax), used for biogas production, located at the same farm in Pavia province (Italy), were selected to analyze the biodiversity variability and the community structure of beetles over a one-year period. Data were acquired by positioning ten pitfall traps per crop field from May 2016 to April 2017. All specimens were classified to species level. A total of 8,903 specimens belonging to 12 families of Coleoptera have been detected over this period. An ordination NMDS analysis and a Permanova Multivariate analysis have been applied. As a result, corn showed a really simplified community, significantly different from A. donax. In the corn field few species dominate, producing a very unbalanced species abundance distribution, typical of disturbed environments. The strong homogeneity of the corn captures produces a small cloud of samples in NMDS representation. In the A. donax field, the beetle community is more diversified, with a very well-shaped species abundance distribution, but the remarkable variation of the samples suggests the presence of a still not well-established community.