The squash bug, Anasa tristis (De Geer), is a major pest of squash, pumpkin, and other cucurbits throughout North America. A. tristis is a piercingsucking feeder that causes extensive foliar wilting and fruit scarring and transmits plant pathogens. Current biological agents to control A. tristis are limited in efficacy, and newer control methods must be developed. Here we present studies of immune system transcripts as the initial step in identifying potentially vulnerable targets for control of gene expression. Following immune stimulation with bacteria, transcript levels of six components of the inducible innate system in adult female A. tristis were measured using quantitative PCR. An antibacterial peptide-encoding transcript, anacin; an enzyme central to melanization, prophenoloxidase; and three sentinel proteins, scavenger receptor, β-1,3-glucan-binding protein, and peptidoglycan-binding protein were upregulated by bacterial elicitation. Expression of a putative immunoregulatory cytokine, astakine, was identified and increased by septic puncture. We also found novel upregulation of an enzyme of central energy metabolism, arginine kinase, in response to septic puncture of A. tristis adults.