OEcology: see ecology.
OEdagus: the penis.
OEnocytes: large yellow cells arranged segmentally in clusters, in each side of body cavity: associated with blood and fat bodies.
OEsophageal bone: a plate below anterior part of oesophagus in Psocidae.
OEsophageal bulb: = sub-clypeal pump; q.v.
OEsophageal diverticula: = food reservoirs (q.v.); but more generally applied also to any sac-like structure connected with the gullet.
OEsophageal lobes: form posterior portion of brain or tritocerebrum.
Oesophageal valve: a funnel-like folding of the oesophagus, extending into the chylific ventricle in some insects, and forming a valve that controls the entrance of food into that organ: = cardiac valvule.
Oesophagus: the gullet: that part of the alimentary canal between the mouth and the crop.
Olfactory: pertaining to the sense of smell: those lobes of the deutocerebrum from which the nerves supplying the antennae arise.