The peritrophic matrix (PM) structural integrity of honey bee larvae (Apis mellifera L. Hymenoptera: Apidae) and monarch butterfly larvae (Danaus plexippus L. Lepidoptera: Danaidae) was disrupted by products from the spore-forming bacterium that causes American foulbrood, Paenibacillus larvae (=Bacillus larvae) and the organism that causes chalkbrood, the spore-forming fungus, Ascophaera apis. This report presents visual evidence of the PM damage caused by the bacterium and the fungus, and it includes a preliminary survey of the enzymes that appear to be involved in the damage-inducing mechanism. Proteases, including cysteine protease, chitinase, collagenase, and proteoglycan-digesting enzymes were investigated.