At least in earlier years 'Insectes Sociaux' accepted manuscripts in French. Not sure whether they still do that now. Otherwise have a look at http://en.wikipedia.org/wiki/List_of_entomology_journals for some journals published in France. Translation to English would certainly make it easier.
Merci à Sean Haughian d'avoir suggéré Écoscience. La revue publie effectivement en français (et an anglais) et est indexée dans Web of Science (facteur d'impact 2012 = 1,354).