Family: Asterolecaniidae

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Common name: Pit scales or asterolecaniids

Field Characters: Pit scales are relatively diverse, but the typical pit scale (genera such as Asterodiaspis, Asterolecanium, Neoasterodiaspis, Planchonia, and Russellaspis) usually has the body of the insect set in a depression or pit in the host tissue and has a white fringe around the body margin. There generally is a swelling around the edge of the scale insect and a translucent often yellow or green test covers the exposed part of the body. Most species of Bambusaspis, Grammococcus, and Polea don't form pits but are similar in other ways. A few uncommon genera form complete galls of various sorts including Abditicoccus, Amorphococcus, Endernia, and Frenchia.

Asterolecanium arabidis                Asterolecanium arabidis                Bambusaspis bambusae
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Diagnosis: Typical asterolecanium-type pit scales are characterized by the presence of 8-shaped pores that are sessile and form a band around the body margin; tubular ducts with a small invagination and a much enlarged truncate filament; anal ring area simplified, rarely with 2 rows of pores; anal area often with lateral sclerotized bar and arch plate; and without legs.

Notes: There are several exceptions to the characters listed above and similar characters occur in species of other families. For example, 8-shaped pores occur in some species of soft scales and 8-shaped pores are absent from adult females of the asterolecaniid genera Endernia, Frenchia, and Grammococcus. Because of the very different structure of the polliniine asterolecaniid taxa they are treated separately and are not included in this section. Asterolecaniidae Cockerell was first used as a family by Enderlein (1914).

Distribution: Pit scales occur in most areas of the world although they seem to be most abundant in the northern hemisphere. Click here for a list of genera and species from the Australasian region, Afrotropical region, Nearctic region, Neotropical region, Oriental region, and Palearctic region.

Hosts: Pit scales are found on a broad diversity of hosts but are especially common on bamboos, oaks, and many species of ornamentals.

Life History: Asterolecaniids apparently have 3 female instars and 5 male instars. They generally are found on the leaves or twigs of the host and often cause some form of host deformation. The exposed portion of the body is usually covered by a clear or transparent test. Eggs are laid under the test and occupy the cavity formed as the adult female shrivels anteriorly. Males are uncommon, but when present develop under a test similar to the female test.

Important references: Borchsenius 1960d; Gill 1993; Russell 1941; Wang 2001.

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