Common name

Lac scales or kerriids

Field characters

Body convex and covered with a thick resinous secretion or a hard horny material; often with lobes or sculpturing. The covering has 3 openings, 2 spiracular or brachial plate openings, and an anal opening; delicate waxy filaments originate from each opening; many species aggregate in large masses that encrust host branches and twigs.

Validation characters

One pair of spiracles conspicuously larger than other; conspicuous brachial plate with many pores; dorsal spine present anterior of anal opening; anal area with associated anal fringe; legs reduced or absent; antennae poorly developed.

Notes

Lac scales are relatively uniform in their morphology and are quite distinctive when compared with other families of scale insects. An introduced species Paratachadina pseudolobata Gullan & Kondo has recently reached pest status in Florida. Kerriidae Lindinger was first used as a family by Lindinger (1937).

Distribution

Kerriids occur in all zoogeographical regions of the world. Click here for a list of genera and species from the Australasian region, Afrotropical region, Nearctic region, Neotropical region, Oriental region, and Palearctic region. They are most speciose in the Oriental region.

Hosts

Lac scales occur primarily on the twigs and branches of trees and woody shrubs.

Life history

Lac scales have 3 or 4 instars in the female and 5 in the male. In the true lac scale, Kerria lacca (Kerr) there are 2 or 3 generations each year. Eggs are laid inside a brood chamber which is formed as the adult female shrivels during the egg-laying process. There may be as many as 1,000 eggs laid by a single female. Eggs hatch and first-instar crawlers emerge from the test through a hole near the anal opening. The crawlers settle on the new stem growth and produce a broad lac test. Females molt 3 times and enlarge the test until it coalesces with the secretions of other females. Males also produce a test, but it is narrow and has a large opercular opening. Adult males emerge through the operculum and may be winged or wingless. Populations may contain as many as 30% males, but they apparently are unnecessary for reproduction. The biology of Tachardiella larreae Comstock has also been studied. There is 1 generation each year, first instars are laid inside the brood chamber, and appear in early spring. Mating occurs in July and eggs begin developing in females in late summer.

Important references

Chamberlin 1923; Colton 1943; Kapur 1958; Kondo & Gullan 2011; Varshney 1970, 1984b, 1990.

Diversity

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