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.
Draw-thread: the silk-producing gland.
Drone: in Hymenoptera; the male bee.
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 -us: double.
Duplicate-pectinate: having the branches of a bipectinated antenna alternately long and short.