We combined spectrophotometry and an original statistical approach to infer bacteria virulence, using the lepidoptera Galleria mellonella as a host model. With this method, it is possible to use a microplate reader to automatize data collection on host survival on batches of 96 samples. The method also allows measurement of pathogen multiplication if GFP labelled bacterial strains are used. Copyright © 2018 Elsevier B.V. All rights reserved.