Second median area: see median area; areola.
Second submarginal nervure: Hymenoptera (Nort.), = radius 5 (Comst.).
Secretion: any matter produced by a gland: in Coccidae, specifically, the waxy, fibrous, cottony or silky substances forming the "scales."
Secretionary supplement: that part of a Diaspid scale extending beyond or around the pellicles.
Secretory: concerned in the process of secretion.
Sectores coronis: the tearing or cutting structures used by the Lepidoptera in working out of a cocoon.
Sectors: longitudinal veins in Odonata, which strike the principal veins at an angle, and usually reach the apex or hind margin: they are radial, subnodal, principal, nodal, median, short, and upper and lower of triangle: all of which see.
Secund: pointing one way: unilateral.
Securiform: triangular-compressed; like the blade of a hatchet.
Sedentary: not active: settled or remaining in one place.