Part 161

Vulvar scale: = v. lamina.

Wart: a spongy excrescence, more or less cylindric, with a nearly truncated tip: the enlarged, common base of a group of seta: in Trichoptera, a pitted elevation.

Wax: a ductile substance excreted by bees and other insects from glandular structures in various parts of the body, used in building cells or in forming a protective covering.

Wax-cutter: the pincer-like structure formed by the hind tibia and metatarsus in social bees.

Wax-glands: any glands in any part of the body which secrete a waxy product in either a scale, string or powder: in Coccidae, the circumgenital and parastigmatic glands; q.v.

Wax-pincer: = wax cutter.

Wax-scale: one of the scales secreted in the wax pocket or gland of a worker bee.

Whitlows: = paronychia; q.v.

Whorl: a ring of long hair arranged around a centre, like the spokes around the hub of a wheel.

Wing, Wings: membranous reticulated organs of flight; one pair, the primaries, attached to the meso-thorax; the other, the secondaries, attached to the meta-thorax.

Wing covers: those parts of the chitinous cuticle of larvae, nymphs or pupae which cover the rudiments of the wings of the imago: the forewings of an imago when they are thicker than the hind wings and cover them when at rest: see elytra; tegmina.

Wings of the heart: the series of diagonal and other muscular fibres above the diaphragm in the pericardial cavity: see pericardial diaphragm.

Wing cells: areas inclosed by veins: reference should be had to the figures illustrating venation and to the special terms applied to the cells.

Winglets: small, concavo-convex scales, generally fringed at tip, under the base of the elytra in Dytiscidae.

Wing-pads: undeveloped wings of pupa or nymph.

Wing-scale: in Hymenoptera, = tegula; q.v.

Workers: the undeveloped females in the social Hymenoptera; also those sexually undeveloped Termites that are not soldiers.

Xanthophyll: the yellow of autumn leaves; one of the substances found in the blood of insects.

Xenobiosis: see symbiosis.

Xerophilous: applied to species living in dry places.

Xylophaga: wood-eaters: applied in several orders.

Xylophagous: feeding in or upon woody tissue.

Xyphus: a spinous or triangular process of the meso-sternum in many Hemiptera, and some other insects.

Yellow: used without modification is sulphur or lemon yellow.

Yolk: the nutritive matter of an egg as distinguished from the living, formative material; = deutoplasm.

Zona: a belt or zone; as of distribution.

Zonite: = arthromere or somite; q.v.

Zooenite or Zooenule: = zonite.