Common name

Giant scales or monophlebids

Field characters

Body large, up to 10 mm or more, generally elongate oval; legs and antennae usually conspicuous and dark.; occurring on the stems, branches, or foliage of the plant; usually with wax covering the body, occasionally without wax; often forming an ovisac or with a marsupium.

Validation characters

Anal tube well developed, with a simple sclerotized ring or band of pores at inner end; cicatrices present; abdominal spiracles present, usually conspicuous; thoracic spiracles without pores in atrium (but often with pores near atrium entrance); legs large and conspicuous; antennae large, 7- to 11-segmented; claw digitules not reaching tip of claw, usually not enlarged apically; not forming a cyst.

Notes

The family Monophlebidae in most American literature has been treated as a subfamily of the Margarodidae, but the enormous morphological and biological variation within the Margarodidae, in the broad sense, has made it necessary to recognize a number of families. The giant scales are very diverse morphologically, but appear to be a monophyletic group. Monophlebidae Signoret was first used as a family by Maskell (1880).

Distribution

Giant scales occur in all zoogeographic regions but seem to be most diverse in tropical areas.

Hosts

Monophlebids occur on a diverse array of plant hosts but usually are found on woody shrubs and trees.

Life history

Giant scales have relatively simple life history patterns compared with cyst forming margarodoids. In general they have 4 female instars and 5 male instars, but unlike most other scale insects, the prepupa is quite mobile and although it may have wing buds, the legs and antennae are well developed (Morales 1991). Drosicha mangiferae Green has 1 generation each year. Eggs hatch in December or January after diapausing in ovisacs in the soil or the duff around the host. First instars move to the leaves and molt 3 times to become adults. Males are indistinguishable from females until the third instar prepupa. The prepupa wanders for a while, forms a waxy test, and molts to the pupal stage. Adults appear in April, mate, and migrate off of the host to the ground where an ovisac is produced and eggs are laid. The life cycle of Icerya purchasi Maskell is similar but developing females lay their eggs directly on the host in a fluted ovisac that is attached to the body of the adult female. Males are uncommon. Females actually are hermaphrodites that frequently inseminate themselves. Adult males mate with females, but it is not clear if their sperm are used for reproduction (Hughes-Schrader 1930). Inseminated eggs produce hermaphrodites and uninseminated eggs produce males. There are 2 or 3 generations each year depending on the climate.

Important references

Chandra, Bhati, and Singh 1987; Hodgson and Foldi 2006; Hughes-Schrader 1930; Morales 1991; Morrison 1928; Unruh and Gullan 2008.

Diversity

Click here for a check list of all monophlebid genera and species.