Dorsopleural suture: Diptera; the lateral suture between dorsal and pleurum from the humeri through the base of the wing: separates the mesonotum from the pleura.
Dorso-ventral: in a line from the upper to the lower surface.
Dorsulum: the mesonotum before the scutellum, with the wing sockets: also, specifically, the meso-scutellum.
Dorsum: the upper surface: in Coleoptera; often confined to meso- and meta-thorax: Odonata; includes mesepisterna and meso- and meta-thoracic terga: Diptera; upper surface of thorax, limited by the dorsopleural sutures laterally, the scutellum posteriorly and the neck anteriorly: Lepidoptera; the lower or inner margin of the wing.
Duct: a channel, tube or canal for carrying a secretion from a gland to the point of discharge.
Ductus ejaculatorius: the single duct or tube formed by the union of the vasa deferentia from each side, through which the seminal fluid is ejected into the vagina.
Dufour's gland: that gland, in Hymenoptera, that secretes the alkaline portion of the poison carried by the sting.
Duodenum: the chylific ventricle; also applied to the first section of the digestive tract just behind entrance of malpighian tubules.
Dupion: a cocoon spun by two silk-worms together; also the coarse silk from such a cocoon.
Duplicate-pectinate: having the branches of a bipectinated antenna alternately long and short.
E: as prefix, is privative and means without.
Ears: organs of hearing, as on the first tibiae or on the first abdominal segment of some Trichoptera.
Ecaudate: without tails or tail-like processes: usually applied to wings : = excaudate.
Ecdysis: the process of casting the skin; moulting.
Ecology: the science of the relation of organisms to each other and to their surroundings: = ethology. { Scanner's comment: Ethology nowadays refers to studies in animal behaviour, not directly to ecology.}
Ectal: belonging or relating to the outer surface.
Ectoblast: the outer wall of a cell; the ectoderm or epiblast.
Ectoderm: the outer layer of skin: the outer layer of the blastoderm, giving rise to the nervous system and to epithelial structures of the body surface.
Ectoskeletal: referring to the outside or exoskeleton.
Ectotrachea: the outer surface or layer of the trachea.