Appearance in life
Scale cover of adult female elongate, shaped like a mussel shell, flat to moderately convex, mid-brown to whitish, with terminal exuviae; sometimes obscured under the epidermis of the host. Scale cover of immature male similar to that of female but much smaller.
Adult female not pupillarial; body elongate and more or less fusiform; usually membranous except for the rather triangular pygidium, but a few species sclerotized on head; lateral lobes of free abdominal segments more or less well developed, sometimes with marginal sclerotized spurs present. Pygidium with prominent median lobes set close together but not zygotic; these lobes with short, slightly divergent inner margins and long, oblique outer margins that may be notched or serrate. Second lobes much smaller than median lobes, often reduced to points or absent; third and fourth lobes absent or represented by serrations only. Ventral paraphyses arising from the median lobes, if present, variously shaped but often transverse; sometimes an additional, club-shaped paraphysis arises from the basal angle or from the middle of the lobe base. Gland spines short, present on pygidial segments and at least abdominal segments III and IV; a small pair always present between the median lobes; replaced by duct tubercles when anterior to abdominal segment II. Anus circular to oval, situated in the anterior quarter of the pygidium; vulva situated at, or just anterior to, centre of pygidium. Marginal macroducts usually numbering 4-6 on either side of the pygidium, never with macroduct present between median lobes; each marginal macroduct enlarged, with a thick sclerotized rim and with the long axis perpendicular to the pygidial margin. Dorsal macroducts smaller than marginal ducts, or represented as microducts, arranged in segmental rows. Submarginal dorsal bosses present or absent. Duct tubercles may be present anterior to abdominal segment II. Perivulvar pores sometimes rather few, present in 5 groups. Stigmatic disc pores present by anterior spiracles only. Antennal setae usually numbering 2 or more.