Abstract
A fungus of the genus Entomophthora attacks female fifth instar nymphs and adults of the alfalfa plant bug, Adelphocoris lineolatus (Goeze). It destroys all the non-chitinized tissues of the abdomen, beginning with the ovaries and fat bodies, but does not invade tissues of the thorax and head. However, perhaps in response to the effects of castration by the parasite, activity in the host's neurosecretory A-cells of the brain ceases and the corpus allatum hypertrophies.