Overview
Adults and larvae of most species of ladybirds are predacious on aphids, mealybugs, scales or other small insects and mites. The Epilachninae, however, are phytophagous,
Epilachna
damaging the foliage of Solanaceae and Cucurbitaceae, including vegetable crops like pumpkin, cucumber, tomato and potato; while the Psylloborini (Coccinellinae) feed on powdery mildews (Ascomycetes: Erysiphales). Among the carnivorous species, several have been used with notable success as agents of biological control.
Rodolia cardinalis
, for instance, saved the California citrus industry from destruction by the cottony cushion scale (
Icerya purchasi
), while other Australian species, such as
Cryptolaemus montrouzieri
,
Rhyzobius ventralis
and
R. forestieri
, were employed in Hawaii and California for the control of a number of scale insects (HEMI: Coccoidea). Species of
Stethorus
are predators of the two-spotted mite (
Tetranychus urticae
) (Britton and Lee 1972).
Some adult coccinellids, when alarmed, feign death and discharge drops of yellow haemolymph, which is toxic to vertebrates, from the tibio-femoral articulations. There are 6 subfamilies: Sticholotidinae, Scymninae, Chilocorinae, Coccidulinae, Coccinellinae and Epilachninae. Among the larger and more commonly encountered Australian coccinellines are
Coelophora inaequalis
,
Coccinella transversalis
and
Harmonia conformis
. [Gordon 1985; Hagen 1962; Hodek 1973; Pope 1979, 1981, 1989; Richards 1981, 1983; Sasaji 1968, 1971.]
Description
Broadly ovate, moderately to strongly convex beetles with pseudotrimerous tarsi (segment 3 reduced, 2 strongly lobed beneath it). Antennae short, weakly clubbed; apical maxillary palp segment almost always large and securiform; femoral lines on first ventrite and sometimes metasternum. Many larger species glabrous and brightly patterned with red or yellow and black or blue; most smaller species more uniformly coloured and finely pubescent.
Larvae elongate, oblong or occasionally broadly ovate and slightly to strongly flattened, usually with transverse row of 6 tubercles or prominences on most abdominal segments and often covered with waxy exudate; some forms are spinose above and may be aposematically coloured like many adults. Antennae very short; mandibles often with sub-basal lobe which probably represents a reduced mola; mala obtuse and usually with
stylus
(specialised, setiferous process); there are paired glandular openings on the thorax and abdomen; tibia usually withs 2 to several expanded setae extending beneath tarsungulus. Pupa obtect and partly enclosed within larval skin, which is attached to substrate by anal end.