design: Qiagen's Dneasy Blood and Tissue kit was used to extract DNA from the gut contents of Vespa velutina larvae. The Leray fragment of the COI region was amplified with the primers mlCOIintF and HCO2198. PCR mix consisted of 25 l OneTaq 2X master mix with standard buffer, 0.5 mg/ml BSA, 5 ng template DNA, 0.2 M of each primer, made up to 50 l with HPLC water. Thermocycling conditions were: initial denaturation at 94 C for 3 minutes, 25 cycles of 94 C for 30 seconds, 46 C for 30 seconds, 68 C for 30 seconds, and a final elongation step at 68 C for 5 minutes. Illumina adapters were added via ligation, resulting in a mix of plus and minus strands in the R1 and R2 files. Demultiplexing was therefore done in two rounds, resulting in four files per sample in which all reads are in their expected orientation (i.e. forward reads are in R1 files).