The average pH for the six species ranged as follows: Leptinotarsa decemlineata (Say), 5.6 to 6.6; Monocesta coryli (Say), 5.7 to 7.3; Leptura sp., 5.5 to 7.1; Osmoderma scabra (Beauv.), 7.5 to 10.2; Passalus cornutus Fabr., 5.9 to 9.0; and Cotnis nitida (L.), 7.6 to 10.1. All measurements were made electrometrically using a one-drop glass electrode. The possibility of a relationship between food and digestive tract pH in Coleoptera is pointed out.