Allux: next to the last joint of tarsus; in Rhynchophora.
Alternation of generations: where a species that occurs in both sexes periodically produces only parthenogenetic females; the latter, in turn, producing the sexed form; occurs in Cynipidae and some Homoptera: see heterogeny.
Altus: above: applied to a part raised above the usual level.
Alulae: Diptera; a pair of membranous scales above the halteres, behind the root of the wing, one above or before the other; the anterior attached to the wing and moving with it, the posterior fastened to the thorax and stationary; see calyptra; squama; squamula; lobulus; axillary lobe; aileron; scale; tegulae: Coleoptera; a membranous appendage of the elytra which prevents dislocation.
Alulet: Diptera: the lobe at basal posterior part of wing; = alar appendage; posterior lobe: and has been used as = alula.
Alutaceous: rather pale leather brown [burnt sienna]: covered with minute cracks, like the human skin.
Alveolate: furnished with cells: deeply pitted.
Alveolus: a cell, like that of a honeycomb.
Amber: a transparent, clear, pale yellowish brown; of the color of amber [a mixture of pale cadmium yellow and a little burnt umber].
Ambient vein: Diptera; the costal vein when it extends beyond the apex and practically margins the wing.
Ambrosia: bee-bread: the food cultures of certain Scolytid beetles.
Ambulatoria: that series of Orthoptera in which the legs are fitted for walking only; Phasmids.
Ambulatorial: fitted for walking or making progress on the surface.
Ambulatorial setae: specialized hairs or bristles, situated on the ventral segments of the abdomen of some Coleoptera.
Ambulatory: moves by walking; formed for walking.
Ametabola -ous: insects without obvious metamorphoses, in which the larvae usually resemble the adult and the pupae are active.
Ametabolion: an insect that has no distinct metamorphoses.
Amethystine -us: bright blue with a reddish admixture; clear like an amethyst [between mauve and lilac].
Amnion: the inner of the two membranes enveloping the embryo.
Amnion cavity: a tube-like insinking from the ventral plate of the embryo, extending cephalad.
Amnion fold: the extensions of the amnion which close the mouth of the amnion cavity in the embryo.